What was required before texas could be annexed by the united states? 1.all the debts texas had acquired had to be paid. 2.both countries had to approve annexation. 3.texas had to agree to abolish slavery. 4.mexico had to approve the agreement officially.

The answer is 2. Both countries had to approve the annexation.
By receiving approvement from its people, Texas also agree to follow all the laws/Regulations that imposed by the states.
After prolonged back and forth negotiations, Texas formally relinquished its sovereignty to the United States on February 19, 1846.

Marshall plan is the answer.