The answer is A. photoperiodism.
Photoperiodism is an organism reaction to the lengths of days and nights. Some plants require longer days, and some require shorter days. By changing the lengths of days and nights, commercial plant growers are able to increase plants productivity.
Tropism is plant growth in a response to a stimulus.
As it name suggests, <em>photo</em>tropism is plant growth in a response to light.
<em>Gravi</em>tropism is plant growth in a response to gravity.
Thigmotropism is plant growth in a response to contact
When conducting legal experiments on animals, a researcher needs to obtain consent from the INSTITUTIONAL RESEARCH BOARD.
Each research institution has research board which sees into uses of animals for research purposes, consent must be obtained from the board before experiments involving usage of animals is carried out.
The answer is; catalyst
These proteins are called enzymes. They work by lowering the activation energy of reactants and hence speed up the biochemical reaction. They are not affected in the process hence one enzyme molecule can catalyze many reactions. An example of such an enzyme is carbonic anhydrase that enables carbon dioxide to dissolve in blood plasma as carbonic acid.
