I believe the answer to this question is D, I am not sure though.
The operon is effectively the center of transcriptional control. In addition to its main structural genes, the operon houses an operator and a promoter. In front of the promoter lies a regulatory gene that produces repressor proteins. When a repressor is in its active state, it binds to the operator.
Hope this helped.
Answer:
reactants come out of a reaction
Hermit crabs live in large colonies so there is no real answer. You can put up to 10 hermits in a 10 gallon aquarium or 4 to 6 in the smallest plastic cage safely. They do eat but very little and can go several days up to two weeks without food. They store water in the back of their shell for moisture for their gills.