Answer:
this is my lazy guess but: human activity, differences in emitted energy from earth, and natural fluctuations. BUT DONT TRUST ME LOOK IT UP IM NOT SMART
It is <span>a salt or ester of pyruvic acid. Here is an image of what it is...
And these
</span><span>Formula: </span><span>C3H4O3</span><span>
Molar mass: </span>88.06 g/mol<span>
IUPAC ID: </span>2-oxopropanoic acid<span>
Density: </span>1.25 g/cm³<span>
Related keto-acids, carboxylic acids: </span>acetic acid; glyoxylic acid; oxalic acid; propionic acid; acetoacetic acid<span><span>Acidity (pKa)</span>: </span><span>2.50</span>
"The manner in which the body changes as a natural result of growing older" is called Aging Process. <span>The human body goes through an assortment of changes as it gets older. Muscles, blood vessels and other tissues lose their elasticity. The heart becomes less efficient, bones become weaker and the metabolism slows down.</span>
They are called nephridia................B
<span />