The antonym of 'profuse' is not on that list, and we don't use the expression 'opt out' to mean 'select' or 'choose' or 'identify.' 'Opt out' means to exercise your option to withdraw or decline.

philanthrope

Opt is short for option. To opt in is to accept or join; to opt out is to decline or reject.

Opt-in means that you are only on a list or in a group if you specifically ask to be. Opt-out means that you are on the list or in the group unless you specifically ask not to be.

opt qty

Decide to or not to do something