The most immediate, but necessarily limited, source of energy for reformation of ATP in muscle cells is ____.

A) aerobic respiration
B) mitochondrial pathways
C) electron transport phosphorylation
D) creatine phosphate
E) anaerobic fermentation

Creatine phosphate is the most immediate source of energy for reformation of ATP in muscle cells because it can donate a phosphate group to ADP, forming ATP, without the need for oxygen or the involvement of mitochondria. However, this process can only sustain energy production for a short period of time before other energy pathways, such as anaerobic fermentation or aerobic respiration, need to be utilized.