Looking at the answer options:

10 hours of line training as commander under supervision, consisting of at least 5 sectors → INCORRECT. It is 10 sectors, not 10 hours.

An operators proficiency check as commander → CORRECT. An OPC is effectively a mini IR, and tests that the pilot is proficient from the left hand seat in dealing with engine failures and successful approaches etc.

An operational proficiency check as commander and as co-pilot → INCORRECT. No need for an OPC as a co-pilot any more.

Special emergency procedures and CRM training → INCORRECT. The emergency procedures are the same so you would already be qualified.

EASA AIR OPS 
ORO.FC.205 Command course

(a) For aeroplane and helicopter operations, the command course shall include at least the following elements:

(1) training in an FSTD, which includes line oriented flight training (LOFT) and/or flight training; 
(2) the operator proficiency check, operating as commander; 
(3) command responsibilities training; 
(4) line training as commander under supervision, for a minimum of:

(i) 10 flight sectors, in the case of aeroplanes; and 
(ii) 10 hours, including at least 10 flight sectors, in the case of helicopters;

(5) completion of a line check as commander and demonstration of adequate knowledge of the route or area to be flown and of the aerodromes, including alternate aerodromes, facilities and procedures to be used; and 
(6) crew resource management training.