Watergate was a major political scandal that occurred in the United States in the 1970s, following a break-in at the Democratic National Committee headquarters at the Watergate office complex in Washington, D.C. in 1972 and President Richard Nixon's administration's attempted cover-up of its involvement.
The main driving force causing glomerular filtration is: A. osmotic pressure of plasma colloids promoting filtration.
To address your question, here's a basic picture of the glomerulus, from Gray's Anatomy. The afferent arteriole is in red, and the efferent arteriole in blue. The glomerular filtration rate (GFR) depends on the pressure difference between the two, which affects the hydrostatic pressure at the glomerulus. Constriction of the afferent arteriole decreases the blood flow into the glomerulus and thus the glomerular hydrostatic pressure, which leads to a decrease in GFR.