Question

a. I am studying here since last January. b. I was studying here since last January. c. I have been studying here since last January.

Answer 1

C.

A is incorrect because “am” is present tense and you are referring to now and the past. Therefore it confuses the tenses.

B is incorrect because it focuses on the past tense only, when you are referring to both the past and present.

This leaves C. C is correct because have been is helpful to connect these two tenses.