Which verb form correctly completes this conversation?

Juan: ¿Qué prefieres que ellos preparen hoy, jugo de piña o de naranja?
Alex: Yo prefiero que _______ jugo de piña.

preparan
preparas
preparen
prepares

Respuesta :

The correct answer is C preparen because they both are talking what 'ellos' will do, not themselves
the answer is.........wait for it.........almost here..............the answer is.............. C.Preparen!!!