AP environmental science.

I really need help with these 2 questions.

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

Want free points and brainliest? answer this correctly and i got you a preventative measure against encountering vehicle malfunctions in the middle of a drive is to a. assess your fitness to drive b. do a quick vehicle pre-check c. clean and wash the vehicle d. deflate and inflate your tires

With my drivers ed ! another name for dash lights is a. vehicle problem indicators b. vehicle warning indicators c. vehicle status indicators d. vehicle caution indicators