It's a tricky one attacking Iran cause they will stop the oil getting out from Saudi for ages just by sinking some ships in the key waterway.
"Within minutes of any attack, Iran's air (see photo) and sea forces could threaten oil shipments in the Persian Gulf as well as the Gulf of Oman. Iran controls the northern coast of the Strait of Hormuz, the narrow waterway through which oil tankers must navigate, and could sink ships, mine sea routes or bomb oil platforms, according to the CSIS report. "