We see the so called " near side " of the moon. Because the moon spins in the exact rotational period we see the same side of the moon every time we look at it .
The correct answer is it lives inside or on a host.
A is incorrect because a parasite steals from the host, without giving anything in return. Much like a leech
C is incorrect because leeches almost always use their host as a food source
D is incorrect because parasites can often dig beneath the host's skin to be hidden from sight
The researcher could look for the presence of proteins, because viruses have a envelope (capsid) composed of proteins that involve their genetic material. The capsid may have a helical or icosahedral structure and is extremely regular. Viroids cannot synthesize any type of protein, so differentiation is possible.
They help absorb nutrients <span />
The answer of the question is citric acid cycle