The answer is: D. Passive transport
Passive transport refers to the movement of chemical substance that pass through the cell membrane without using any energy, This ability exist in all living cells and utilizing the process of osmosis to move from a less concentrated environment to a more concentrated one.
A moon has its own gravitational pull and an asteroid dosent.
If you’re referring to the current Coronavirus pandemics, the reasons we want to mass vaccinate the population is to stop the spread by making it harder to find a host that it can use to replicate. The more times the RNA virus replicates, the more mutations are generated, the more likely a strain, that can escape the any immunity developed, can occur. Herd Immunity is what will help reduce the ability of a virus to spread. If the virus can’t find a host to replicate in (because the host is immune to the virus) the harder it is for the virus to spread.
