Why does athlete pushes the earth backward fith his feet and hands just before the race starts

So that the earth can exert a forward force on him too and push him forward.
This is an example of Newton's third law of motion.

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.