The resting membrane potential is a measure of what?

The correct answer is the measure of the electrical charge difference across the cell membrane. The resting membrane potential is primarily determined by the distribution of ions, particularly sodium, potassium, chloride, and others, across the cell membrane. This difference in ion concentration creates a voltage difference between the inside and the outside of the cell, which is essential for various cellular functions, including nerve impulse conduction and muscle contraction.

In a typical cell, the inside is negatively charged compared to the outside due to the unequal distribution of ions, especially the higher concentration of potassium ions inside and higher concentration of sodium ions outside. This voltage difference is crucial for maintaining cellular homeostasis and enabling cellular communication.

The other options do not accurately describe the resting membrane potential. The physical size of the cell does not influence the electrical charge difference across the membrane. The concentration of nutrients or temperature of the cell may affect metabolic activities but are not directly related to the resting membrane potential. Thus, B is the most accurate choice for describing this fundamental aspect of cellular physiology.