i would say A.
the double bond in an unsaturated fatty acid produces a kink in the molecule. The bend in the carbon chain, however, is much more pronounced in the cis isomer compared to the trans isomer. For this reason, cis fatty acids (and triacylglycerols made from them) do not solidify like trans fatty acids. Due to the larger bend, the cis isomers cannot line up next to one another in as ordered a fashion as the trans isomers and can be more flexible.
examples of vestigial structure would include the tail bone, wisdom teeth, and the appendix. hope this helps :)
The natural water sample contains only one type of bacteria.
