To force a bill out of committee, a/an petition must be signed by a majority of the representatives.
a. calendar
b. release
c. discharge
d. amendment

To force a bill out of committee, a DISCHARGE petition must be signed by a majority of the representatives.

Answer; 
C. discharge
To force a bill out of committee, a discharge petition must be signed by a majority of the representatives.

Explanation; 
Discharge petitions are often associated with the U.S House of Representatives and used when the committee chair refuses to place a bill or resolution on the Committee's agenda which results to the bill being unreported and not subject to the scrutiny of the House.

It might be the second one