Identify the segment with a grammatical error.
She learnt / how to play a piano / when she was in Class 6th.

Correct option is A

The error is in option (a) "how to play a piano."
· The article "a" should not be used before "piano" because musical instruments generally take the definite article "the" in such contexts.
· The correct phrase should be: "how to play the piano."
Grammatical Rule Used:
· When referring to musical instruments in a general sense, use "the" instead of "a" (e.g., "She plays the violin beautifully.").
Example:
Incorrect: "He knows how to play a guitar."
Correct: "He knows how to play the guitar."
Thus, the correct sentence is: "She learnt how to play the piano when she was in Class 6th."