Which can be used to prevent initial entry of bacteria into the body

Inflammation.

Explanation:

The same reason you would die if your body temperature gets too high. Our bodies are meant to perform at an optimal temperature because the cells within our body perform cellular processes perfectly at that temperature. Same goes with bacteria. At high temperatures, proteins degrade and denature and fail to function. Your membrane transport proteins break apart: you can't get things in or out of your cells. You can no longer establish electron gradients for ATP synthesis: your body can no long provide itself with energy. Your ribosomes denature and fail to carry out protein synthesis: you cannot build new cells to replace the dying ones. You are dead.

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.