A crane operator is distracted while lifting an air conditioning unit while lifting it to the top of an office tower under construction, and drops the unit, damaging several vehicles parked on the street below. The accident is immediately reported to the crane operator's employer's CGL insurer, who begins an investigation. According to the CGL policy conditions, the insurer can deny coverage if it does not get full cooperation in its investigation from

$($Search Chapter $9)$

a$.$ the owners of the damaged vehicles.

b$.$ any witnesses of the accident.

c$.$ the crane operator and his employer.

d$.$ the crane operator and any witnesses of the accident.