Final answer:
Depolarization is the process where positive charges enter the cell, making the resting membrane potential less negative and causing it to move toward zero.
Step-by-step explanation:
The term that is best defined as an influx of positive charges, causing the resting membrane potential to become less negative, i.e., more positive, is depolarization. During depolarization, positively charged ions, such as Na+ or Ca2+, enter the cell. This movement of positive ions is due to a higher concentration outside the cell compared to the inside and results in the membrane potential moving toward zero. This is in contrast to hyperpolarization, where the cell becomes more negative, and repolarization, where the cell returns to its resting potential after depolarization has occurred.