The random thermal motion of molecules from a region of higher concentration to a region of lower concentration is called diffusion. the rate of diffusion across a barrier is defined by fick’s law of diffusion:

Explanation:

Fick's law of diffusion describes the times course of transfer of matter from a region of high concentration to a region of lower concentration separated by a thin barrier membrane.

Mathematically:

where:

q = quantity of solutet = time A = membrane surface areac = concentrationD = diffusion coefficientdx = membrane thickness = concentration gradient

Julia would be observing a. static electricity was caused by her sweater rubbing against her shirt and transferring electrons. she didn't touch anything metal, so that would cancel out b.she most likely didn't rub her sweater against her hair either, so that cancels out c.she also didn't scoot across the carpet while trying to take her sweater off, that cancels out d.so that leaves a.a. is correct.