You are writing a PyTorch training script on a machine with a CUDA-enabled GPU. You have correctly identified the device and moved your model to it. However, when you run your script, it crashes on the forward pass with a RuntimeException, indicating that the model's weights and the input data are on different devices. Review the following code snippet and determine the single line of code that must be added to the ---BLANK --- to fix this specific error. import torch import torch.nn as nn # 1. Setup device and move the model to it device = torch.device("cuda" if torch.cuda.is_available() else "cpu") model = nn.Linear(in_features=64, out_features=10).to(device) optimizer = torch.optim.Adam(model.parameters(), lr=0.001) # 2. Create a batch of input data (defaults to CPU) # This simulates data coming from a DataLoader input_batch = torch.randn(32, 64) # [batch_size, feature_size] # 3. Perform a training step optimizer.zero_grad() # --- BLANK --- # The following line causes the error: # "RuntimeException: Expected all tensors to be on the same device, # but found at least two devices, cuda:0 and cpu!" outputs = model(input_batch) # ... loss calculation and backward pass would follow What line of code should be placed in the --- BLANK --- to resolve this device mismatch?

(D) input_batch = input_batch.to(device)

(C) input_batch = input_batch.requires_grad_(True)

(E) torch.set_default_tensor_type('torch.cuda.FloatTensor')

Introduction to Deep Learning and Generative AI · Quiz 1 · 26 Oct 2025 · September 2025 term

Question 4: You are writing a PyTorch training script on a machine wi…

Question 4

+2 marksOne correct option

You are writing a PyTorch training script on a machine with a CUDA-enabled GPU. You have correctly identified the device and moved your model to it. However, when you run your script, it crashes on the forward pass with a RuntimeException, indicating that the model's weights and the input data are on different devices.

Review the following code snippet and determine the single line of code that must be added to the ---BLANK --- to fix this specific error.

python

1import torch
2import torch.nn as nn
3
4# 1. Setup device and move the model to it
5device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
6model = nn.Linear(in_features=64, out_features=10).to(device)
7optimizer = torch.optim.Adam(model.parameters(), lr=0.001)
8
9# 2. Create a batch of input data (defaults to CPU)
10#    This simulates data coming from a DataLoader
11input_batch = torch.randn(32, 64) # [batch_size, feature_size]
12
13# 3. Perform a training step
14optimizer.zero_grad()
15
16# --- BLANK ---
17
18# The following line causes the error:
19# "RuntimeException: Expected all tensors to be on the same device,
20# but found at least two devices, cuda:0 and cpu!"
21outputs = model(input_batch)
22# ... loss calculation and backward pass would follow

What line of code should be placed in the --- BLANK --- to resolve this device mismatch?

A
model.cuda()
B
input_batch.cuda()
C
input_batch = input_batch.requires_grad_(True)
D
input_batch = input_batch.to(device)
E
torch.set_default_tensor_type('torch.cuda.FloatTensor')

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Correct answer

D
input_batch = input_batch.to(device)

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Question 4 of 20 in the IIT Madras BS Introduction to Deep Learning and Generative AI (Deep Learning and GenAI) Quiz 1 paper sat on 26 Oct 2025, in the September 2025 term (IIT M DIPLOMA AN EXAM QDD2 26 Oct 2025). It carries 2 marks.

Question 4: You are writing a PyTorch training script on a machine wi…

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