What is the main function of the immune system?

A. to circulate blood cells
B. to destroy pathogens
C. to secrete tears
D. to keep the skin moist

to destroy pathogens

Explanation:

the immune system helps fight off unwanted bacteria & anything your body doesn't recognize. whenever you're sick, your immune system is fighting off your sickness

the density would be a smaller number.

not  

cuba  

russia  

iraq  

el salvador  

explanation:

known as the land of volcanoes, el salvador has visit seismic tremors and volcanic movement. it is the main nation in central america that does not have a coastline on the caribbean sea. about portion of all salvadorans live in the wide open. they are poor and don't have power or running water in their homes. in 1525, pedro de alvarado, a lieutenant of cortés's, vanquished el salvador. el salvador, with alternate nations of central america, pronounced its freedom from spain on sept. 15, 1821, and was a piece of a league of central american states until the point when that association broke up in 1838.