I'm going to say since I cannot see the graph i'm guessing that it shows an enzyme at its peak and lowering so i'm going to say the first one 1) There is a specific pH range in which the enzyme effectively lowers the reaction's activation energy
A substance floats if it is less dense, or has less mass per unit volume, than other components in a mixture. For example, if you toss a handful of rocks into a bucket of water, the rocks, which are dense compared to the water, will sink. The water, which is less dense than the rocks, will float. Basically, the rocks push the water out of the way or displace it. For an object to be able to float, it has to displace a weight of fluid equal to its own weight.
Water reaches its maximum density at 4 C (40 F). As it cools further and freezes into ice, it actually becomes less dense. On the other hand, most substances are most dense in their solid (frozen) state than in their liquid state. Water is different because of hydrogen bonding.
The answer they want is "Telophase" without quotes
This link should help it has all the information you need...
https://arxiv.org/pdf/1511.08792.pdf
