Which one of the following is categorised as a parasite in the true sense?

Some plants have a habit of harbouring ants to save themselves from damage by other animals,which is known as:

$A$ high density of elephant population in an area can result in

The sea anemone and the clown fish are an excellent example of which of the following?

The stimuli through which a dancing scout bee communicates the location of a food source to other worker bees in a hive are

Choose the correct statements regarding population interactions between two species.
$A$. In both parasitism and commensalism,only one species benefits and the other species is harmed.
$B$. Both species benefit in mutualism.
$C$. Both species benefit in commensalism.
$D$. In parasitism,only one species benefits and the other species is harmed.
$E$. In amensalism,one species is harmed and the other is unaffected.