From experience with my best friend, I´d say C.
Answer is C. By exposure to mucous membranes of an infected person
Blood borne pathogens are microorganisms which are transmitted through the blood. Blood borne infections can be transmitted in the blood or body fluid such as saliva, mucus that can be mixed with blood and cause diseases like Hepatitis B and HIV (Human immuno deficiency virus). The most common method of transmission of pathogen through blood of an infected person when enters in the body of a healthy person through open wound.
A blood test measuring CK levels can help determine how injured his skeletal muscle is.