Extracellular fluid contains up to 10,000 times more calcium than intracellular fluid, and yet all cells continue to pump out even more calcium. They could only do this by means of pinocytosis. facilitated diffusion. osmosis. active transport.

ACTIVE TRANSPORT

Explanation:

ACTIVE TRANSPORT is the movement of molecules across the cell membrane from a region of lower concentration to a region of higher concentration, against it's concentration gradient.

Active transport involves the use of energy from ATP( Adenosine triphosphate).

There are 2 types of active transport:

A. Primary (direct) active transport: this involves the direct use of ATP to drive the movement of molecules across the membrane.

B. Secondary (indirect) active transport: involves using primary active transport for a molecule to drive another molecule along the electrochemical gradient.

Active transport.

Explanation:

Active transport allows the transport of ions as calcium or other molecules from a place of low concentration to a place of high concentration, it is against the concentration gradient and it needs the help of energy to transport the molecules.

The transport of calcium from a place of low concentration, the inside of the cell, to a place of a higher concentration, the extracellular fluid, is an active transport that goes against the concentration gradient, so it is against the natural equilibrium between the inside and the outside of the cell, which is necessary for some reactions.

o conteúdo de calor de um sistema é igual à entalpia apenas para um sistema que é constante

i think it's letter a.