Which choice completes the text so that it conforms to the convention…

Source Texts

Text

Proto Omotic—a protolanguage, or ancestral language of a family of descendant (daughter) languages—is said to be the common ancestor of all Ta-Ne-Omotic languages. This designation is _____ Proto Omotic is only postulated, its characteristics being inferred from the linguistic properties of its nineteen daughters.

Which choice completes the text so that it conforms to the conventions of Standard English?

hypothetical: however,

hypothetical, however,

hypothetical. However,

hypothetical, however;