Answer:
Orobanchaceae
Explanation:
You don’t have to know about the characteristic of the family to inferred which is the plant family that they ask you for, the key part of the question is in the last paragraph:
“Medicinal species include Verbascum, Euphrasia, Pedicularis, and Veronica.”
The taxonomic ranges for organisms comes from species, genus, family, order, class, phylum, kingdom and lastly domain. If they give you the common name of the species, you only have to search for which family belongs these species.
They all belong to the Orobanchaceae Family