Answer:
D. a target cell's response is determined by the components of its signal transduction pathways
Step-by-step explanation:
Signal transduction pathway is a set of steps from the ligand binding (e.g. hormone binds to its receptor) to the cell response. The chain reaction that occurs after the ligand binding can include mechanisms such as phosphorylation, dephosphorilation, activation of messengers, degradation etc which together can make a whole huge network.
The cell response at molecular level can include change in gene expression (changes in transcription and translation), protein changes (conformational, post-translational modifications, change in location).