Which is likely reason why the governments of Iran and Iraq have historically had disputes over rights to the Shatt al-Arab?

A- The Shatt al-Arab is sacred land to both Iranians and Iraqis.

B- The Shatt al-Arab is rich in potash and phosphates.

C- The Shatt al-Arab is a strategic waterway.

D- The Shatt al-Arab is a strategic mountain location.