A shift from a reliance on .............. to reliance on …….. was pivotal in the evolution of all vertebrates.

Options

A. notochord; a backbone
B. filter feeding, jaws
C. gills, lungs
D. all of the above

Answer

To answer the question "A shift from a reliance on .............. to reliance on …….. was pivotal in the evolution of all vertebrates," we can break down the components involved in the evolution of vertebrates.

### Step-by-Step Solution:

1. **Understanding the Context**:
- The question is about the evolutionary transition that occurred in vertebrates. This involves understanding what early vertebrates relied on and what they shifted to.

2. **Identifying the Initial Reliance**:
- Early vertebrates, particularly those in aquatic environments, relied on **filter feeding**. This method of feeding involves filtering small particles from the water, which was common in primitive organisms like sponges.

3. **Identifying the Shift**:
- As vertebrates evolved, they developed more complex feeding mechanisms, particularly the evolution of **jaws**. Jaws allowed vertebrates to grasp and consume larger prey, marking a significant shift in feeding strategy.

4. **Considering Respiratory Structures**:
- In addition to feeding, early vertebrates relied on **gills** for respiration in water. Over time, some vertebrates evolved to use **lungs**, allowing them to exploit terrestrial environments.

5. **Finalizing the Answer**:
- Therefore, the shift can be summarized as a transition from reliance on **filter feeding** (and gills) to reliance on **jaws** (and lungs). This transition was pivotal in the evolution of vertebrates, enabling them to adapt to various environments.

### Complete Answer:
A shift from a reliance on **filter feeding** (and gills) to reliance on **jaws** (and lungs) was pivotal in the evolution of all vertebrates.

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