The sudden death of brain cells when their blood supply is interrupted is called
a. a heart attack.
b. a stroke.
c. hypertension.
d. atherosclerosis.

Option B, a stroke

Explanation:

A stroke is caused by an interrupted blood supply which leads to the death of brain cells. The strokes are of two types –

a)Ischemic attack– In this a blood clot causes blocking of blood vessel. Ischemic attack is of two types –  

1.Thrombotic – This occurs primarily due to blood clotting in any vessel or artery

2.Embolic. This occur when a part of thrombus travels from its original site and blocks some other artery  

b)Hemorrhagic stroke – In this a blood vessel burst inside a brain thereby causing brain hemorrhage.

carbohydrates: (starches and sugars) composed of carbon, hydrogen, and oxygen.

lipids: (fats, oils, and waxes) are made of carbon and hydrogen atoms.

nucleic acids: contain hydrogen, oxygen, nitrogen, carbon, and phosphorus. they are polymers of nucleotides. a nucleotide has three parts, a 5-carbon sugar, a phosphate     (-po⬇️4) group, and a nitrogenous base.

proteins: made up of nitrogen, carbon, hydrogen, and oxygen. they are polymers of amino acids.

i'd say that the moon rock is about 2.2 billion years old.