Is this bad? lol?

Facial shaving brushes are either bulb-shaped or fan-shaped. an experiment is to be conducted to determine whether the lather thickness is the same for both types of shaving brushes. in previous studies, it was determined that shaving brush size (small, medium, large) is associated with lather thickness, but shaving brush type (wolf whiskers, maggard razors, frank shaving, and so on) is not associated with lather thickness. how could the experiment best be conducted? by blocking on shaving brush size by blocking on shaving brush type by blocking on shaving brush shape by blocking on lather thickness without blocking

Who wants free brainliest and free points for this drivers ed question! if answered correctly! in the u.s. highway numbering system, north-south routes have numbers that end in a. "0" b. "1" c. a letter d. an even number

98 points! include an answer and in advance!