Which ocean resources are second in economic value to oil

Salt and oil is the only thing i can think of ...

Which of the following is NOT an energy resource obtained from the ocean?

1. C, Coal

The Persian Gulf, the Gulf of Mexico, and the North Sea are all known for their reserves of what ocean resource?

2. A, Oil

Which ocean resources are second in economic value to oil?

3. A, Sand and gravel 100%