He said it would be convenient for him to meet me there.

Answer: Option C

Convenient : fitting in well with a person's needs, activities, and plans.
Inadvisable : likely to have unfortunate consequences; unwise.
Objectionable : arousing distaste or opposition; unpleasant or offensive.
Troublesome : causing difficulty or annoyance.
Desirable : wished for as being an attractive, useful, or necessary course of action.

Antonym of Convenient is Troublesome