What have similar membranes?
PDAs humans viruses crocodiles animals sharks fur seals insects
A B C D E F G H
Viruses are enveloped by similar membranes.
viruses have similar membranes 
What have similar membranes? (A) PDAs (B) humans (C) viruses (D) crocodiles (E) animals (F) sharks (G) fur seals (H) insects