conjugate the verb preferir in all forms in the present tense

what takes place in the conjugation that makes this verb a stem changing verb

The verb "preferir" is a stem-changing verb in the present tense. In this case, the vowel 'e' in the stem changes to 'ie' in all forms except for the first and second person plural (nosotros/as and vosotros/as) where the vowel 'e' remains unchanged.

Here are the conjugations of "preferir" in the present tense:

- Yo prefiero (I prefer)
- Tú prefieres (You prefer)
- Él/Ella/Usted prefiere (He/She/You formal prefers)
- Nosotros/Nosotras preferimos (We prefer)
- Vosotros/Vosotras preferís (You all prefer)
- Ellos/Ellas/Ustedes prefieren (They/You all formal prefer)