Read the passage from gulliver's travels. the method is this: in an acre of ground you bury, at six inches distance and eight deep, a quantity of acorns, dates, chestnuts, and other mast or vegetables, whereof these animals are fondest; then you drive six hundred or more of them into the field, where, in a few days, they will root up the whole ground in search of their food, and make it fit for sowing, at the same time manuring it with their dung: it is true, upon experiment, they found the charge and trouble very great, and they had little or no crop. however it is not doubted, that this invention may be capable of great improvement. which excerpt from the passage is the best example of understatement?

it is not doubted, that this invention may be capable of great improvement.

Explanation: An understatement is the presentation of something as being smaller or less important that it really is, in this excerpt the phrase "this invention may be capable of great improvement" makes seem like the method already works but it could be improve (it doesn't say that it needs improvement, just that it may be capable of improvement), when in reality, reading the explanation of the method, we realize that it is absolutely ineffective, as "they found the charge and trouble very great, and they had little or no crop", so if this technique could work in any way, it would need a massive improvement.

So that is the answer because they make seem that the improvement is not really necessary or it isn't a big deal.  

it is not doubted, that this invention may be capable of great improvemnt

Explanation:

The method is this: in an acre of ground you bury, at six inches distance and eight deep, a quantity of acorns, dates, chestnuts, and other mast or vegetables, whereof these animals are fondest; then you drive six hundred or more of them into the field, where, in a few days, they will root up the whole ground in search of their food, and make it fit for sowing, at the same time manuring it with their dung: it is true, upon experiment, they found the charge and trouble very great, and they had little or no crop. However it is not doubted, that this invention may be capable of great improvement.

i believe the answer is b. we