The correct option is C black walnut trees and herbaceous plants
When two different species interact, it can be a beneficial, detrimental or neutral interaction.
If out of the two interacting species, one gets inhibited or destroyed (harmed) and another one is unaffected (neither harmed nor benefitted), then such a type of interaction is called amensalism.
This type of interaction has been observed between black walnut trees and herbaceous plants. The black walnut tree secretes chemicals called juglones that inhibit the growth of the herbaceous plants like tomatoes and blueberries. The black walnut trees are unaffected by this interaction.
The cactus feeding moth is the predator of prickly pear cactus. In this interaction, the moth is benefited and the cactus is harmed. This type of interaction is called predation.
In some shallow South American lakes, the flamingoes and resident fishes compete for zooplankton which is their common food. This type of interaction is called interspecific competition and has a negative effect on both the interacting species.
Barnacles and whales exhibit commensalism, in which one species is benefited and the other is neither benefited or harmed. Barnacles are found on the back of whales. The whales are neither benefited or harmed by barnacles but barnacles are benefited from this interaction as whales provide shelter, free ride and access to plenty of food.