Osmotrophy is found in

The correct option is Taenia.

Step-by-step Explanation:

1. Understanding Osmotrophy:
Osmotrophy is a method of nutrition where an organism absorbs dissolved organic nutrients directly from its surrounding environment through its body surface. Unlike holozoic organisms, osmotrophs do not ingest solid food particles or have a specialized digestive tract for mechanical breakdown and internal digestion of food.

2. Analyzing the Options:
- Taenia (Tapeworm): Taenia is an endoparasite residing in the gut of its host. Because it lives in an environment already rich in digested nutrients (the host's intestine), it has completely lost its own digestive system (no mouth, no gut). Instead, it absorbs pre-digested nutrients directly through its outer body covering (the tegument) via active transport and diffusion. This is a classic example of osmotrophy.
- Pila (Apple Snail): Pila is a free-living mollusc that feeds holozoically using a specialized scraping organ called the radula.
- Palaemon (Prawn): Palaemon is an aquatic crustacean that feeds on small organisms and organic debris, utilizing a complex digestive system.
- Asterias (Starfish): Asterias is an echinoderm that captures prey and digests it, often by everting its stomach outside its body to engulf food.

Therefore, among the given options, only Taenia exhibits osmotrophic nutrition.