Which excerpt from the passage is the best example of understatement?

Which excerpt from the passage is the best example of understatement?

A) in an acre of ground you bury, at six inches distance and eight deep, a quantity of acorns, dates, chestnuts

B) then you drive six hundred or more of them into the field, where, in a few days, they will root up the whole ground

C) they found the charge and trouble very great, and they had little or no crop it is not doubted,

D) that this invention may be capable of great improvement