In the following questions, a part of the sentence is given in bold. Below are given alternatives to the bold part at 1,2,3 and 4 which may improve the sentence. Choose the correct alternative.
What you have been doing in the workshop since last month ?

Options

A. have you done
B. you have done
C. have you been doing
D. No Improvement

Answer

C

Explanation

(3) The structure of the sentence will be as follows : ... Have + Subject (you) +been+ Verb+ ing (doing) ... ?
The sentence is in Present Perfect Continuous Tense.
Hence, have you been doing is the right usage.