In the question, a sentence has been divided into four parts (A), (B), (C) and (D). Read the sentence to find out if there is any grammatical error in it. The error, if any, will be in one part of the sentence. Mark the part as your answer. If there is no error, the answer is 'No error'. Ignore the errors of punctuations if any.

Riya and her twin /(A) lost they parents/(B) when they were just/(C) five years old./(D)