Find out whether there is any grammatical error in below sentence. The single biggest gainer in this process / was ITC's Gold Flake Kings sales are estimated / to have moved up from 50 million to 200 million sticks per month during 1987 and last year.

• A. to have moved up from 50 million to 200 million sticks per month during 1987 and last year
• B. was ITC's Gold Flake Kings sales are estimated
• C. The single biggest gainer in this process
• D. No error

Answer: (B)