Answer:
The correct answer is A.
Explanation:
Membrane fluidity can be increased by lipid chains with carbon-carbon double bonds (unsaturated phospholipids). They are more fluid than lipids that are saturated because unsaturated double bonds make it harder for the lipids to pack together.
Also higher temperatures can increase membrane fluidity because lipids acquire thermal energy, this results in many arranges and rearranges of the membrane and therefore makes it more fluid.