There are many reasons why domestic fuel sources are preferable to international fuel sources. The biggest reasons why domestic is preferable is because of the security risks involved.
The struggle for the independence of Texas took place over many years, although the actual war that achieved independence from Mexico was relatively brief. In the 1820s, Stephen Austin won the Mexican government's approval to bring American families into the sparsely settled Tejas (Texas) region.
The answer to your question is B
Prior to the 25th amendment, the constitution was not very clear that the Vice-President takes over for the President. It is in the 25th amendment allows for the Vice President to become president in the event of death, resignation, removal from office or impairment that prevents the current president from fulfilling his or her duties.