B. because they are not manufactured by the body
Answer
Hi,
A. Radioactive markers
Explanation
Hershey and Chase used specific radioisotopes to form a trace of the two important components of the virus in its life cycle. The 32P was used to identify the DNA while the 35s labeled the proteins.DNA strands have a sugar phosphate where as protein contains sulfur.
Best wishes!
Parasitism
Parasitism can be defined
as a relationship between species in which one organism (parasite) lives on or
in another organism which is the host, causing it some harm without immediately
killing it. Thus, parasitism is a kinds of close, symbiosis and persistent
biological interactions.
