Which arteriole radius adjustment was more effective at compensating for the effect of low blood pressure on the glomerular filtration rate? explain why you think this difference occurs?

Answer 
Increasing the afferent arteriole radius.

Explanation;
Increasing the afferent arteriole radius or decreasing the efferent arteriole would compensate for the effect of reduced blood on the glomerular rate. However, Increasing the afferent radius had a greater effect than decreasing the efferent radius because there was a greater increase in glomerular pressure.