The first vertebrates were :

Options

A. bony fish
B. jawed fish
C. jawless fish
D. both (a) and (b)

Explanation

To solve the question "The first vertebrates were:", we can follow these steps:

### Step 1: Understand the Evolutionary Timeline
- Begin by noting the timeline of life on Earth. The first cellular forms appeared around 2,000 million years ago, followed by invertebrates around 500 million years ago.

### Step 2: Identify the Emergence of Vertebrates
- Recognize that vertebrates emerged later in the timeline, specifically around 350 million years ago.

### Step 3: Determine the Characteristics of Early Vertebrates
- Focus on the characteristics of the first vertebrates. The earliest vertebrates were jawless fish, which are classified under the superclass Agnatha.

### Step 4: Analyze the Options Given
- Review the options provided:
- A) Bony fish
- B) Jawed fish
- C) Jawless fish
- D) Both A and B
- Since the question asks for the first vertebrates, we can eliminate bony fish and jawed fish, as they evolved later.

### Step 5: Conclude with the Correct Answer
- Based on the evolutionary history and the characteristics of early vertebrates, the correct answer is C) Jawless fish.

### Final Answer:
The first vertebrates were jawless fish.

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