Population Interactions

• Calotropis: It is a weed that grows in abandoned fields. Calotropis produces poisonous cardiac glycoside so that no cattle or animal hinders them
• Pisaster: Pisaster ochraceus feeds on invertebrates like mussels and snails. Pisasters have tube feet and a mouth beneath their central disk. Pisasters use their tube feet to pry on the prey and extend their stomach out of their mouth and into the shell of the prey to digest it.
• Monarch Butterfly: These butterflies are increasingly distasteful to their predators because of the chemicals present in their bodies. The butterfly feeds on a poisonous weed to acquire this chemical during the caterpillar stage.
• Frogs: Species of frogs use different defence mechanisms to lessen the impact of predation. Frogs are cryptically coloured or camouflaged so that they do not get easily detected by predators.

So, the correct option is (B): 1-(s) 2-(p) 3-(q) 4-(r)