Krupa and Kavya studied (1)/ in the Delhi Public School (2)/ and so does Kamnya. (3)/ No error (4)

Answer

3

Explanation

did will replace does because -
the first clause isin Past Tense, the following clause will also be inP ast Tense.
Hence, Simple Past Tense will be used. Hence, and so did Kamya is the right usage.