When may the crankcase ventilation pipes or oil drain pipes of two or more engines be connected?

a. Propulsion engines under 1000 shaft horsepower may share a common crankcase vent provided the oil drains remain separate.
b. In most cases it is desirable and cost effective for propulsion engines to share a common crankcase ventilation and monitoring system.
c. No interconnection may be made between the crankcase ventilation pipes or oil drain pipes
d. None of the above are correct.