Final answer:
The rate at which the mRNA is degraded in the cytoplasm is a factor that determines the amount of protein synthesized from that mRNA molecule due to its effect on mRNA stability and translation duration.
Step-by-step explanation:
The factor that plays a role in determining the amount of protein made using a given mRNA molecule is d. the rate at which the mRNA is degraded. The stability of the mRNA in the cytoplasm influences how long it can be translated before being broken down, thus affecting protein synthesis levels. Factors that contribute to mRNA stability include the length of its poly-A tail and the presence of a 5' cap. It is important to note that ribosomes, transcription factors, introns, and DNA methylation may also influence gene expression, but they do not directly determine the amount of protein produced from an mRNA molecule once it is in the cytoplasm ready for translation.