Consider the reaction below. H O single bonded to C double bonded above to O and to the right to the bottom left of a benzene ring. The ring is bonded from the upper right to a C double bonded above to O and to the right to O H. H O bonded to C H Subscript 2 Baseline C H Subscript 2 Baseline bonded to O H. Arrow pointing with bond H Subscript 2 Baseline O beside it pointing down to H O bonded to C double bonded above to O and to the right to the bottom left of a benzene ring. The ring is bonded from the upper right to a C double bonded above to O and to the right to O bonded to C H Subscript 2 Baseline C H Subscript 2 Baseline bonded to O H.
This reaction eventually forms this product.

A bond from left to O single bonded to C double bonded above to O and to the right to the bottom left of a benzene ring. The ring is bonded from the upper right to a C double bonded above to O and to the right to O bonded to C H Subscript 2 Baseline C H Subscript 2 Baseline bonded to O bonded to C double bonded above to O and right to the upper left corner of a benzene ring. The ring is bonded from the lower left to C double bonded above to O and single bonded right to O bonded to CH Subscript 2 Baseline C H Subscript 2 Baseline bonded right to O bonded to C double bonded above to O and right to the lower left of a benzene ring, which is bonded from upper right to C double bonded above to O and single bonded right to O bonded to C H Subscript 2 Baseline C H Subscript 2 Baseline bonded to O.
Which type of reaction is represented by these diagrams?

elimination
substitution
addition polymerization
condensation polymerization