Several very distantly related species (e. g., bats, birds, insects) have evolved the capability of flight. The most recent common ancestor of insects and vertebrates likely lived over 500 million years ago and was flightless. This independent evolution of flight in multiple, distantly related taxa is an example of what evolutionary process/pattern

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.

i might be wrong but i think its a. let me know if i’m right and have a good rest of your day!