Organisms that grow best under elevated pressure like you would find in the deep ocean are

The answer is extreme piezophile. This organism cannot grow at the pressure hydrostatic of 1 atm. And this piezohilic requires pressure hundredth of atmosphere for growth. The counterpart of piezophile is oligotrophy this organism grows only in the best place with a very low levels of nutrients.

an active site is a region that is present on an enzyme where the reactants or the substrate molecules we can say bind and experience a chemical reaction. the substrate is basically a reactant whose concentration is changing and that is converting into a product after binding at the active site of an enzyme

the answer is d. chordata