its préfèrent (C)
preferer is a first group verb
and for first group verb
je- you remove the r at the end eg parler will become parle(je parle)
tu- you add s( tu parles)
elle- same as je (elle parle)
il- same as elle
nous- add ons (parlons)
vous- add ez (parlez)
elles/ils - add ent(parlent)
so preferent
i hope you understand
