I'm unable to see images or diagrams. However, I can help you understand how to determine the correct relative positions of the Sun, Moon, and Earth based on the phase of the Moon you observed.
1. **New Moon**: The Moon is between the Earth and the Sun, and the illuminated side is facing away from Earth.
2. **Waxing Crescent**: The Moon is slightly east of the Sun (from Earth's perspective), with a sliver of light visible.
3. **First Quarter**: The Moon is at a right angle to the line between the Earth and the Sun. Half of the Moon is illuminated.
4. **Waxing Gibbous**: The Moon is still moving away from the Sun, but more than half is illuminated.
5. **Full Moon**: The Earth is between the Moon and the Sun, with the entire face of the Moon illuminated.
6. **Waning Gibbous**: The Moon is past full, moving towards the last quarter, but still more than half is lit.
7. **Last Quarter**: Like the first quarter but on the opposite side, half of the Moon is illuminated.
8. **Waning Crescent**: The Moon approaches a new phase, with a small sliver of illumination left.
If you can describe the phase of the Moon that the students observed, I can help you determine which diagram (A, B, C, or D) is correct.