Organic compound, any of a large class of chemical compounds in which one or more atoms of carbon are covalently linked to atoms of other elements, most commonly hydrogen, oxygen, or nitrogen. ... The few carbon-containing compounds not classified as organic include carbides, carbonates, and cyanides
The answer to the question above is letter "C. prostaglandins". They are lipids that are made at a site where there is a damage in tissue or infections. These hormones control some of the vital processes in the body such as blood flow, inflammation, formation of blood clots, and others.
From the perspective of an employee, the effective channeling of work-related information and concerns: is best conveyed through one's immediate supervisor.
The potassium remaining is 1/4 of the original, so two half lives have passed.
One half life = 1.25 billion years
Two half lives = 1.25 x 2 = 2.5 billion years
The tools are 2.5 billion years old.