At what temperature does the maximum activity of enzyme b occur

Answer

Enzymes have an optimum temperatue at which they work fastest. For mammalian enzyme this is about 40°C, but there are enzymes that work best at very different temperatue.

Forexample, enzymes from arctic snow flea work at - 10°C, and enzymes from thermophilic bacteria work at 90°C. up to the optimum temperatue the rate increases geometrically with temperature. The rate increases because enzyme and substrate molecules both have more kinetic energy so collide more often and also because more molecules have sufficient energy to overcome the activation energy.

Enzyme can even works in ice, though the rate is extremely slow due to the very slow diffusion of enzyme and substrate molecules through the ice lattice.