A right-handed patient complains of elbow pain which is aggr…

A right-handed patient complains of elbow pain which is aggravated when turning lids to open jars that are tightly closed.  PROM of the elbow and forearm is within normal limits (WNL) and pain-free.  Joint play is unaffected.  Of the options below, which isometric muscle test is most likely to be weak and painful?