I know you. (make it complex)
A
I know what are you.
B
I know who are you.
C
I know you.
D
I know who you are.
Correct Answer: I know who you are.
Simple sentence কে complex করার নিয়ম sub + verb + relative pronoun (who, which, that) + sub + verb অর্থাৎ সঠিক complex form know who you are.