The correct answer is option C, that is, vasoconstriction.
Vasoconstriction refers to the narrowing of the blood vessels resulting from contraction of the muscular walls of the vessels, in specific the small arterioles and the large arteries.
The constriction of the efferent arteriole reduces the flow of blood out of the glomerulus, and this enhances the glomerular hydrostatic pressure and results in an increase in glomerular filtration rate.
