Which of the Following Is True Regarding Addition Polymerization

Which of the following is true regarding addition polymerization?

A) It occurs in three stages: initiation,margination,and condensation.
B) Monomers have a core of two silicon atoms joined by a double bond.
C) One carbon atom has two hydrogen atoms attached,and the other carbon atom has attached to it one hydrogen atom and one reactive group called a free radical.
D) The reaction produces by-products such as water,hydrogen gas,or alcohol that may compromise the physical properties or handling characteristics.