By 1838, all of the following central american countries became sovereign republics except:
a. honduras.
c. nicaragua.
b. el salvador.
d. costa rica.

By 1838, all of the following Central American countries became sovereign republics except El Salvador. The correct option among all the options that are given in the question is option "b". The country of El Salvador got its independence in the year 1841. The other countries in the question had already got their independence by 1838.

The answer is option a. boundary line drawn by pope alexander iv in 1493.