Hi there!
The best possible scenario for the giraffes with longer necks to survive would be one in which all the lower leaves somehow disappear! This would mean only giraffes with longer necks can eat therefore those will have a better chance of surviving. Luckily the answer that fits that perfectly would be...
D. Monkeys swarm in and tear off all of the lower leaves to use for shelters.
Answer:
Electron transport chain and chemiosmosis/ oxidative phosphorylation
The root word of Unicellular already tells you the answer. Uni means only one cell. So the answer is one cell.
Answer:
to take precise measurements and do experiments
