In the following question, a sentence / a part of sentence is underlined. Below are given alternatives to the underlined part which may improve the sentence. Choose the correct alternative. In case no improvement is required, choose "No Improvement" option.
Two of the biggest corporate firms in the world are Apple and IBM `ul("which both are")` in the computer business.

Options

A. 1.which are both
B. 2.both of which are
C. 3.which are
D. 4.No imrpovement

Answer

B