Describe a Cycloaddition Reaction

Describe a cycloaddition reaction.

A) The reactant has lost a sigma bond,the product has a new sigma bond,and the pi bonds have rearranged.
B) The product contains a new ring,with two less sigma bonds,and two more pi bonds than the starting material.
C) The product contains a new ring,with two more sigma bonds,and two less pi bonds than the starting material.
D) The product contains a new ring,with one less sigma bond,and one more pi bond than the starting material.
E) The product contains a new ring,with one more sigma bond,and one less pi bond than the starting material.