Those chemicals absorbs heat from the surrounding while reacting
The clade which is most likely to survive a series of catastrophic events over time is D. a clade with many distantly related and diverse species.
This is because this will ensure they survive given that they are so different, yet closely related.
I'm pretty sure:
a) pepsin optimal pH: 3 and lipase optimal pH:8
b) No, because the stomach needs to be acidic and have an acidic pH but lipase is considered alkaline because its optimal pH is between 8-14 meaning it's an alkaline.
Not sure if this is any help but I hope it helped a little bit! :)