GATE CSE 2026 Session 2 Q13: Meaning of a Turing machine deciding a language

Which one of the following statements is equivalent to the following assertion?

Turing machine $M$ decides the language $L \subseteq \{0,1\}^*$

Try it: multiple choice: exactly one correct option

Wrong answer costs 1/3 mark in GATE.

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Answer: D (official GATE 2026 final answer key)

Concept used: A decider halts on every input, accepting exactly the strings of $L$ and rejecting the rest.

First step: Check whether each option alone pins down both halting and the correct accept/reject behaviour.

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Source: official GATE 2026 Session 2 CS question paper and final answer key, organised by IIT Guwahati. Question paper · Answer key