Which of the following character is not found in all the chordates:

Options

A. Diaphragm
B. Coelom
C. Pharyngeal gill clifts
D. Dorsal nerve cord

Answer

To determine which character is not found in all chordates, we need to analyze the options provided:

1. **Dorsal Nerve Cord**: This is a characteristic feature of all chordates. It is a hollow nerve cord located along the back of the organism, which develops into the central nervous system (brain and spinal cord) in vertebrates.

2. **Notochord**: This is another defining feature of chordates. It is a flexible rod-like structure that provides support. All chordates possess a notochord at some stage during their development.

3. **Pharyngeal Gill Slits**: These structures are present at some stage of development in all chordates. They are openings that occur in the pharyngeal region and can develop into gills in aquatic species.

4. **Diaphragm**: The diaphragm is a muscular structure that separates the thoracic cavity from the abdominal cavity. However, it is only found in mammals. Not all chordates possess a diaphragm.

Based on this analysis, the character that is not found in all chordates is:

**Answer: A. Diaphragm**