The director had a derisive attitude towards some of the members of the committee.

Answer: Option B

Derisive : expressing contempt or ridicule.
Enthusiastic : having or showing intense and eager enjoyment, interest, or approval.
Respectful : feeling or showing deference and respect.
Deprecatory : expressing disapproval; disapproving.
Encouraging : giving someone support or confidence; supportive.

Antonym of Derisive is Respectful