In biological interactions,what does the interaction type $(+, 0)$ represent?

Mild grazing of plants by herbivores:

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.

Which of the following is an example of predation?

Given below are two statements.
Statement $I$: $Calotropis$ growing in abandoned fields is never consumed by cattle and goats.
Statement $II$: $Calotropis$ produces highly poisonous cardiac glycosides.
In light of above statements,select the most appropriate answer from the option given below.

While explaining interspecific interaction of population,$(+)$ sign is assigned for beneficial interaction,$(-)$ sign is assigned for detrimental interaction and $(0)$ for neutral interaction. Which of the following interactions can be assigned $(+)$ for one species and $(-)$ for another species involved in the interaction?