What creates a positive charge inside the cell during a nerve impulse? A. Gated sodium channels open and sodium ions flood into the cell.

B. Negatively charged ions leave the cell and make the inside positive.

C. Carbon dioxide molecules break apart and become ions to create an overall positive charge.

D. Across the synapse, positively charged ions of many different elements flow into the cell.​

a gated sodium channels open and sodium ions flood into the cell

the answer is "a.) well–developed vascular system."

explanation:

the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to test the hypothesis, and development of a conclusion that confirms, rejects, or modifies the hypothesis.