What borders mexico on all four sides of its sides

On the East you have the Gulf of Mexico that merges with the Atlantic Ocean.

 On the West you have the Gulf of California, which merges with the Pacific Ocean.

North of Mexico, when looking at a map, the part that separates Texas from Mexico, there is the Rio Grande.

Down South, you have Guatemala and Beliz, which also borders Mexico.

Hopefully this helped and good luck. I don't know how technical your teacher wants your answer to be, so I tried to be technical that way he/she cannot say you're wrong in your responses. Once again, good luck.