Through simple diffusion, down the concentration gradient.
Explanation:
The phospholipids of the membrane are amphipathic with hydrophillic heads and hydrophobic tails. Other polar molecules cannot go through this hydrophobic interior. Since small uncharged lipids are non polar and hydrohobic, they are able to go through the membrane without the help of transport proteins. Therefore, the last two options can be ruled out because facilitated diffusion includes the use of a protein. Diffusion involves molecules moving down the concentration gradient so the second option can be ruled out.
According the Mendelian research, it is always good to work with large sample size because small sample size are prone to deviations. Small sample sizes easily get affected by genetic forces such as genetic drift, selection, immigration etc.
