Questions

Add negative keywords to the ad group to reduce irrelevant impressions.

Crop Rotation is the practice of growing a series of dissimilar or different types of crops in the same area in sequenced seasons. It is done so that the soil of farms is not used for only one set of nutrients. It helps in reducing soil erosion and increases soil fertility and crop yield. The British agriculturist Charles Townshend (1674–1738) popularised this revolutionary technique in the 18th century.

A lower CPA may be accompanied by lower sales volume, reducing overall profit.

The trick here is to follow the structure of the statement. The blank is followed by 'of' and thus the blank will take a filler that can be followed grammatically by 'of' and also manages to give a proper meaning. On the basis of these filters, none of the options except option 2 makes any sense.