You are on a cargo vessel carrying portable tanks of dangerous cargoes in bulk.Which statement is TRUE （)_.

A. If the tanks are pumped out while remaining on board，each hose connection must have a minimum of three bolts
B. If the tanks are off loaded，no more than two tanks may be lifted together in a hoist
C. When transferring sulfuric acid，you must display a red flag by day whether at anchor or moored
D. All electrical equipment within 10 feet horizontally must be explosion proof or intrinsically safe