I need help with this questions

Environmental impacts on evolution : mastery test

Matthew decided he wanted to hike up mount everest. on his way to the top, it began to snow and the temperature dropped to -10°f. matthew forgot to wear a heavy jacket so his body began to shiver beyond control. in this case, matthew's body shivering is the to a drop in temperature. * 0 points reflex stimuli responce environmental facto

Q: a: in sexually reproducing animals, once fertilization of the egg takes place, the exists as a single cell until cell division begins