The answer is a, because the population number has increased.
Carbon is special and unique because it is able to form different compounds with a lot of elements, including itself. When it bonds with itself, this is possible because of the concept of hybridization. It is the mixing of atomic orbitals into a new hybrid orbital. In this case, methane is formed through the sp³ hybridization.
A lot of people take a low dose of aspirin every day to lower their risk of a further heart attack or stroke.
