UPSC Prelims 2026 · GS Paper I
Question 42: Science and Technology
Which of the following statements with regard to Large Language Models (LLMs) used in machine learning is/are correct ?
- 1.LLMs assign probabilities to the next possible words and then pick the one with the highest probability.
- 2.LLMs process data through mathematical optimization to minimise prediction errors.
- 3.LLMs produce unbiased outputs.
Select the answer using the code given below :
AnswerUPSC’s answer is (b).
LLMs are trained by mathematical optimisation (gradient descent) that minimises prediction error. When generating text they assign probabilities to the possible next words (tokens) and then choose from them, usually the likely ones, so statements 1 and 2 are accepted. LLMs learn from human-written data and inherit its biases, so they do not give unbiased outputs and statement 3 is wrong.
- 1. LLMs score possible next words by probability and pick one.
- 2. Training is mathematical optimisation to reduce prediction error.
- 3. They inherit biases from their training data.
How you could have got this
- If you were sure statement 2 is correct, (a) goes: it leaves 2 out.
What you needed to know: Training is mathematical optimisation to reduce prediction error.
- Then, if you were sure statement 3 is not correct, (c) and (d) go: each of them includes 3.
What you needed to know: They inherit biases from their training data.
Only (b) is left. You didn’t need statement 1.
This follows UPSC’s provisional key; the final key could change it.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) Incomplete: statement 2 on optimisation is also correct.
- (b) Right: next-word probabilities and error minimisation.
- (c) Wrong: statement 3 is false, as LLMs reflect biases in their training data.
- (d) Wrong: statement 3 is false.
Only the provisional key (27 May 2026) was found; the final key replaces it when found.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2026, General Studies Paper I, Series A. The paper on upsc.gov.in.