<span>metabolic
carbon balance and zonation of sublittoral
macroalgae </span>
C.<span>trees going dormant in winter to survive unfavorable conditions</span>
Answer:
Answer is D - cAMP.
Explanation:
cAMP is a small molecule that functions as an intracellular signaling molecule - a second messenger. The first messenger would be the thing that activated the GPCR (e.g. a hormone). The GPCR is a signal transducer (converts extracellular signal to intracellular signal). Once activated, the GPCR activates adenylate cyclase which can be called a signal effector - it is an enzyme that produces cAMP.
C. Genetic variation
Bacteria are very numerous, and random mutation of bacterial DNA generates a wide variety of change, including resistance. It happens through mutation and selection. Not only are they capable of sharing genetic bits of DNA to related and unrealted species they can develop ways to remove the antibiotic before it reaches its intended area via biochemical pumps or enzymes to inactiavte the antibiotic.