How do pairs of skeletal muscles work together?
a. both muscles contract at the same time.
b. both muscles extend at the same time.
c. while one muscle in the pair contracts, the other returns to its original length.
d. one muscle in the pair pulls on a bone, while the second muscle pulls on the
first muscle.

Which of the following accounts for someone who has had regular herpesvirus-mediated cold sore or genital sore flare-ups? a) re-infection by a closely related herpesvirus of a different strainb) re-infection by the same herpesvirus strainc) copies of the herpesvirus genome permanently maintained in host nucleid) copies of the herpesvirus genome permanently maintained in host cell cytoplasm