Choose the most effective revision for the underlined part of the sentence in the question. If no revision is necessary, choose "Leave it as is."

My mom and dad have been married for twenty years happily.

A) Happily, my mom and dad have been married for twenty years.
B) My mom and, happily, my dad have been married for twenty years.
C) Leave it as is.
D) My mom and dad have been happily married for twenty years.