Yes D is the correct answer
subordinate or dependent clause
AFTER THE CEREMONY. - this phrase is an adverb phrase.
Adverb phrase is a group of words that act as an adverb. It modifies a verb, adverb, or adjective and can tell "how", "where", "why", or "when".
In this case, the adverb phrase tell "when". When did the bride left with the groom? After the ceremony.