I need help on my AVID work, the subject I’m choosing is ELAR and I don’t know how to do a TRF

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

Which of the following entities ensure that national security policies are carried out? check all that apply.

B. speculate about one positive way and one negative way that this boundary has affected the geographical units it separates over time.