Which of the following must be true for hydrocarbons to be trapped by salt diapirs?
a. The salt diapirs must be located beneath a impermeable cap rock to prevent the hydrocarbons from escaping.
b. The hydrocarbons must have migrated towards the salt diapirs due to buoyancy and structural traps.
c. The salt diapirs must create a physical barrier that prevents the hydrocarbons from moving further through the rock layers.
d. The hydrocarbons must be of a specific molecular size and composition that allows them to be trapped by the salt diapirs.