Which one of the following groups of animals is bilaterally symmetrical and triploblastic?

Provide the appropriate technical term for the following descriptions:
$(a)$ Blood-filled cavity in arthropods.
$(b)$ Free-floating form of cnidaria.
$(c)$ Stinging organ of jellyfish.
$(d)$ Lateral appendages in aquatic annelids.

Based on cellular mechanisms, there are two major types of regeneration found in animals. Which one of the following is the correct example of the type mentioned?

The figures $(A-D)$ show four animals. Select the correct option with respect to a common characteristic of two of these animals.

Which of the following species is correctly matched with its two characteristics and phylum/class?

Choose the incorrect statement.