Answer:
A The mating of two particular sheep to produce thicker wool
Explanation:
Selective breeding, also known as artificial selection, is the process in which people will choose two parent organisms to breed and create offspring with desired characteristics. In this case we want the sheep to breed and produce thicker wool.
It is a part of the cell cycle.
The cell membrane is composed of a phospholipid bilayer.
The cell membrane is primarily composed of a mix of proteins and phospholipids
Phospholipids are a major component of cell membranes. They a head and a tail. The head is hydrophilic (attracted to water) and the tail is hydrophobic (repelled by water).
They form a bilayer in which their hydrophilic heads face the aqueous cytosol and extracellular fluid while their hydrophobic tails face away from the cytosol and extracellular fluid.
The lipid bilayer is semi - permeable
I am not entirely sure what you mean by "responding variable" but I'm going to guess it was the vinegar since it has been used as a perservative for years.
Hope that helps in some way.