The correct answer is Option 2: Pitcher plant.

A pitcher plant is an insectivorous plant, meaning it obtains nutrients by trapping and digesting insects. Let`s delve into the detailed reasoning behind this choice:

1. Passion flower plant: While passion flowers are known for their unique and intricate flowers, they are not typically classified as insectivorous plants. Instead, they rely on attracting pollinators, such as bees and butterflies, to aid in their reproduction. Passion flowers produce nectar, which attracts these insects, but they do not trap and digest them for nutrients.

2. Pitcher plant: Pitcher plants are well-known insectivorous plants. They possess specialized pitcher-shaped leaves that contain liquid, which serves as a trap for insects. The rim of the pitcher is often slippery, making it difficult for insects to escape once they have entered. The liquid inside the pitcher plant may contain enzymes that aid in the digestion of captured prey. Some pitcher plant species even have adaptations like downward-pointing hairs and waxy surfaces that prevent insects from crawling out. This unique adaptation allows pitcher plants to supplement their nutrient intake with the nutrients obtained from the insects they trap.

3. Night queen: Night queen, also known as night-blooming cereus or Selenicereus grandiflorus, is a species of cactus. While night queen flowers are large and fragrant, they are not insectivorous plants. They rely on nocturnal pollinators, such as moths and bats, to transfer pollen between flowers. Insects are not trapped or digested by night queen plants for nutrient acquisition.

4. Flame of the forest: Flame of the forest, also known as Butea monosperma, is a flowering tree native to the Indian subcontinent. It produces vibrant orange-red flowers and is not classified as an insectivorous plant. Flame of the forest relies on insects, such as bees and butterflies, for pollination, but it does not trap and digest insects for nutrients.

In conclusion, the insectivorous plant among the given options is the Pitcher plant (Option 2). Its specialized leaves, shaped like pitchers, enable it to trap and digest insects, thus providing additional nutrients to support its growth and development.