Why does matter exists?

  In September 2016 a new result was announced that bears on the dominance of matter over antimatter in the universe. But before discussing the discovery, It wants to review what particle physics has to say about matter and antimatter. There are three types of fundamental particles in the universe: leptons, quarks, and force-mediating bosons. The first two of these are fractional-spin fermions that can have the form of either matter or antimatter.

i'm pretty sure it is letter c.) car

a 20-cm-long, cylindrical graphite (pure carbon) rod is inserted into an oxidizing atmosphere at 1145 k and 1.013 x 105 pa pressure. the oxidizing process is limited by the diffu- sion of oxygen counterflow to the carbon monoxide that is formed on the cylindrical surface.