Animal Kingdom

Step 1: Understanding the Concept:
This question requires knowledge of the life cycles of various invertebrates to identify the larva specific to jellyfish (Phylum Cnidaria, Class Scyphozoa).

Step 2: Detailed Explanation of Options:
- Amphiblastula: This is a free-swimming larval stage of certain sponges (Phylum Porifera).
- Ephyra: This is a juvenile, free-swimming medusa stage of a jellyfish. It is produced asexually by the budding (strobilation) of a polyp stage called a scyphistoma. The ephyra matures into the adult jellyfish.
- Redia: This is a larval stage in the life cycle of flukes (Phylum Platyhelminthes, Class Trematoda), which develops within a snail host.
- Rhabditiform: This is the name given to the first-stage larva of many nematodes (Phylum Nematoda), such as hookworms and roundworms.

Step 3: Final Answer:
Based on the analysis, the ephyra is the correct larval/juvenile form associated with the jellyfish life cycle. Therefore, option (B) is the correct answer.

Step 1: Understanding the Concept:
Sponges (Phylum Porifera) have a cellular level of organization with different cell types specialized for various functions. This question tests the knowledge of these specialized cells and their roles.

Step 2: Detailed Matching:
- A. Collar cells (Choanocytes): These are flagellated cells that create water currents for feeding and respiration. They also play a role in reproduction; they can transform into spermatocytes or surround developing sperm to form a spermatocyst. So, A matches with III.
- B. Trophocytes: These are amoeboid cells that are responsible for digesting and distributing food to other cells. They function as special nurse cells, nourishing other cells, including developing gametes. So, B matches with II.
- C. Pinacocytes: These are flattened, epithelial-like cells that form the outer surface (pinacoderm) of the sponge. They are contractile and can regulate the size of the osculum and pores, acting like sphincters to control water flow. So, C matches with I.
- D. Thesocytes: These are amoeboid cells that are specialized for food storage. They accumulate food reserves like glycogen, lipids, and proteins. So, D matches with IV.

Step 3: Final Answer:
The correct set of matches is A-III, B-II, C-I, D-IV. This corresponds to option (D).