How monarch butterfly develop ability to protect itself by releasing poison?

By feeding on a poisonous weed.

The correct answer is option (3) - By feeding on a poisonous weed.

The Monarch butterfly is highly distasteful to its predator (bird) because of a special chemical present in its body. Interestingly, the butterfly acquires this chemical during its caterpillar stage by feeding on a poisonous weed.

The brightly hued wings of the Monarch Butterfly acts as a “warning sign” to deter hungry predators.

These butterflies are plummeting toward extinction due to landscape-scale threats from pesticides, development and climate change.