The correct option is A added
The word 'eliminated' refers to completely removing or getting rid of something.
Option A, added refers to denoting an additional element.
Option B, improved refers to having become or been made better.
Option C, deleted refers to removing or eradicating.
Option D, shortened refers to making or becoming shorter.
Thus, according to the meaning, the word 'added' is the opposite of the word 'eliminated'.