What does pestilence means as it is used in the following lines form Act V, Scene of Romeo and Juliet?

Friar John: Going to find a bare foot brother out, One of our order to associate me, One of our order, to associate me, Here in this city visiting the sick, And finding him, the searchers of the town, Suspecting that we both were in a house Where the infectious pestilence did reign, Seal'd up the doors, and would not let us forth; So that my speed to Mantua there was stay'd.
A. danger
B. enemy
C. plague
D. thoughts

C. plague