If the microvilli in the proximal tubule were to decrease in
a- urine production would increase.
b- the greater amount of microvilli would be found in the distal tubule.
c- fewer solutes would be found in the urine.
d- urine production would decrease

D- urine production would decrease

Explanation:

The proximal tubule is the portion of the nephron in kidneys which begins from the renal pole of the Bowman's capsule to the beginning of loop of Henle. It consists of the luminal brush border which  is enclosed within with densely packed microvilli forming a border, thus giving the brush border cell its name.

The microvilli greatly increase the luminal surface area of the cells, presumably facilitating their reabsorptive function as well as putative flow sensing within the lumen.

The primary function of Microvilli is to increase the cellular surface area for absorption to take place, and once the surface area increased, the volume ratio would be decreased. As a result diffusion would occur at a faster rate and urine production would increase.

Unlike when there are decrease in number of microvilli, this would also affect the ratio of diffusion, eventually there would be decrease in urine production.