Which organ forms in the third trimester?kidneysearslungsheartIn 2006, approximately what percentage of schools taught students how to use a condom?40 percent60 percent75 percent85 percent

D) better spellers i would think

Answercerebrospinal fluid;

Immunization is the introduction of a foreign substance to provoke  the immune response system.  immunizations are the same as vaccinations. it introduces foreign (but dead/ weakened) illnesses to train the body to fight against them. specific viruses and bacteria have specific antigens, antigens act sort of like name tags. these name tags the immune system recognize what's dangerous to the body and what's safe.