<span>The muscle at the end of the esophagus is not able to close, which allows stomach acid and digested food to go back up into the esophagus. </span>
There are convergent,divergent and transform boundaries and convergent sits in the subduction zone and the divergent is two plates moving apart from each other and transform us where plates slide passed each other? Hope it helps I tried.
True, viral STIs are not curable and can only be controlled with medications