Xi needs to stay awake another hour to study for his english final, so he drinks several cups of cola. when he's done studying, he finds that he can't sleep even though he wants to, he feels agitated, his muscles twitch, his heartbeat is irregular, and he feels nauseated. what is causing xi to feel this way?

The answer is caffeine.

Explanation:

Cola drinks have caffeine in their composition. Even though the amount is not so high (8mg per 100g) when compared to other dirnks, if someone drinks several cups of cola, he/she will most likely experiment some of caffeine's side effects:

- it triggers the release of adrenaline, which can cause the person to feel anxious or nervous;

- since caffeine increases alertness, falling asleep gets more difficult, leading to insomnia;

- rhabdomyolysis or the breakdown of damaged muscle - too much caffeine in a short period of time can cause damaged muscle fibers to enter the bloodstream;

- caffeines raises blood pressure and heart rate.

1 - a

2 - a

3 - c

4 - b

5 - d

i believe the answer is b.