Answer:
The last choice:
Leave the stem viv, and then add the verb endings -o, -es, -e, -imos, -ís, or -en to the stem.
Explanation:
When conjugating regular Spanish verbs (in this case present tense), the only part of the infinitive (meaning any Spanish verb word ending with an -ar, -er, or -ir) you want to take out would be the -ar, -er, or -ir endings. The rest of the word, or the stem, would be left alone. Therefore, the last choice would be correct.
