The subkingdom Parazoa consists of:

Options

A. radially symmetrical sponges, jellyfishes, and their relatives
B. only animals that do not feed by ingestion
C. animals with protostome-type development
D. animals lacking tissues and organs

Explanation

To answer the question "The subkingdom Parazoa consists of:", we will analyze the provided options step by step.

### Step 1: Understand the Definition of Parazoa
Parazoa is a subkingdom within the animal kingdom that includes organisms that are simpler in structure compared to those in the Metazoa subkingdom. They are characterized by a lack of true tissues and organs.

**Hint:** Remember that Parazoa includes organisms that are less complex than those in Metazoa.

### Step 2: Evaluate the Options
Now, let's evaluate each of the options provided:

1. **Radially symmetrical sponges, jellyfish, and their relatives** - This option includes organisms that are not part of the Parazoa. Jellyfish belong to the phylum Cnidaria, which is part of Metazoa.

**Hint:** Identify which organisms belong to Parazoa and which belong to Metazoa.

2. **Only animals that do not feed by ingestion** - While Parazoa includes simple organisms, this statement is too broad and does not accurately describe the defining characteristics of Parazoa.

**Hint:** Consider the feeding mechanisms of organisms in Parazoa.

3. **Animals with protostome type development** - Protostome development is a characteristic of many Metazoan animals, not Parazoa. Parazoa does not have a defined developmental pathway like protostomes or deuterostomes.

**Hint:** Recall the developmental pathways associated with different animal groups.

4. **Animals lacking tissues and organs** - This option correctly describes Parazoa. Organisms in this subkingdom, such as sponges (phylum Porifera), are characterized by their lack of true tissues and organs.

**Hint:** Focus on the defining structural characteristics of Parazoa.

### Step 3: Conclusion
After evaluating all the options, the correct answer is **"animals lacking tissues and organs."** This accurately describes the organisms classified under the subkingdom Parazoa.

**Final Answer:** The subkingdom Parazoa consists of animals lacking tissues and organs.