Final answer:
C-Diff is the infectious agent that is transmitted specifically through direct contact with an environment surface, differentiating it from the other options which involve vectors or respiratory droplet transmission.
Step-by-step explanation:
The infectious agent in the options provided that is transmitted strictly through direct contact, which can include when the infectious agent is present on an environment surface, is C-Diff (Clostridioides difficile). C-Diff is a bacterium that is known to spread through spores that can survive on surfaces for extended periods. Direct contact with these contaminated surfaces can lead to infection, making thorough cleaning and handwashing crucial in preventing the spread of C-Diff. On the other hand, Lyme disease is transmitted through a vector (ticks), the Rubella Virus is generally spread through respiratory droplets, and the Varicella-Zoster virus, which causes chickenpox, can be spread through airborne transmission as well as by direct contact with the rash.