A protein kinase can phosphorylate an enzyme and activate it by

Signal transduction

Explanation:

A signal molecule binds to a receptor.

A conformational change in the signal-receptor complex activates an enzyme.

Second messenger molecules are released.

Protein kinases are activated.

Target proteins are phosphorylated.can be defined as the process in which a physical or chemical signal is transmitted through a cell as a series of molecular events inform of protein phosphorylation are catalyzed by protein kinase and this ultimately result into a cellular response. However, the protein that is responsible for the detection of stimuli is commonly refers to as receptors or sensor.

it's c. (to reduce the greenhouse effect/carbon gasses)

helicase, i think thats it