<h2>Right answer: vivir</h2>
Firstly, is important to note that a verb in <u>infinitive </u>has two parts:
-The ending: <em>ar, er, ir</em>
-The stem, which is everything else (<u>except the ending</u>, of course)
For example, the Spanish verb <em>decir</em> (to say):
The ending is <u>ir</u>
The stem is <u>dec</u>
Now, some Spanish verbs change their <u>stem</u> in a predictable way when they are conjugated. These are called stem-changers or <u>stem-changing verbs.</u>
In this type of verbs, all forms of the verb will undergo a stem change except for <em>nosotros/nosotras</em> (we) and <em>vosotros/vosotras </em>(you)
There are three basic different ways in which the stem of a verb can change in the <u>present tense</u>:
-From <u>e</u> to <u>ie</u>
-From <u>o</u> to <u>ue</u>
-From <u>e</u> to <u>i</u>
According to the explanation above, the only verb of the list that is not a stem-changer is <em>vivir </em>(to live), because <u>this verb does not follow the rules.</u>
The ending of the verb is ir and the stem is viv.
Let's prove it by <u>conjugating this verb in present</u> with the diferent <u>personal pronouns.</u> Note the stem <u>viv</u> keeps the same:
1st person singular Yo: <u>viv</u>o
2nd person singular (informal) Tú: <u>viv</u>es
2nd person singular (formal) Usted: <u>viv</u>e
3rd person singular El/Ella/eso/esa: <u>viv</u>e
1st person plural Nosotros: <u>viv</u>imos
2nd person plural Ustedes (In latinAmerica): <u>viv</u>en
2nd person plural Vosotros (In Spain): <u>viv</u>ís
3rd person plural Ellos/Ellas: <u>viv</u>en