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

Answer: (A)