In the writing process, proofreading is part of the a. Writing step b. Revising step c. Prewriting step

B. Revising Step

Explanation:

You are not writing when you proofread because proofread means (according to the Merriam - Webster Dictionary):

to read and mark corrections in (something, such as a proof)

and prewriting is before you write.

To read and mark corrections is basically revising so its in B. Revising Step

B

Explanation:

proofreading is part of revising step