Huh? Not Tools > Options, but Tools > Protect document. Are you saying you do not have this? Tools > Options > Protect is not for forms. It will not protect for forms, this is a document protection.
You do not unprotect by selecting the section. You do with the Sections button.
As sawedoff stated, Tools > Protect document should give you a choice to protect for Forms, with a Sections button beside it.
Gerry