Blood of Pheretima is red with haemoglobin in plasma.

Explanation:
Haemoglobin is an iron-containing protein found in red blood cells (RBCs) that is responsible for carrying oxygen from the lungs to the tissues and carbon dioxide from the tissues back to the lungs. It gives blood its red color.

Pheretima, commonly known as earthworm, is an invertebrate animal that belongs to the phylum Annelida. Earthworms have a closed circulatory system, meaning that their blood is contained within blood vessels and does not directly come into contact with body tissues.

Now let's discuss why the correct answer is option 'D' - red with haemoglobin in plasma.

1. Haemoglobin in Pheretima:
- Pheretima possesses red blood cells (RBCs) or erythrocytes, which contain haemoglobin.
- Haemoglobin is a pigment that binds to oxygen and gives blood its red color.
- Since the blood of Pheretima contains haemoglobin, it is expected to be red in color.

2. Distribution of haemoglobin:
- Unlike vertebrates, earthworms do not have specialized blood vessels to carry oxygenated blood. Instead, oxygen transport occurs through the plasma.
- Haemoglobin in Pheretima is dissolved in the plasma, which is the liquid component of blood.
- Therefore, the haemoglobin in Pheretima's blood is present in the plasma and not within corpuscles.

3. Color of blood in Pheretima:
- Due to the presence of haemoglobin in the plasma, the blood of Pheretima appears red.
- The red color is a result of the interaction between haemoglobin and oxygen, forming oxyhemoglobin.
- When oxygen is bound to haemoglobin, it gives a bright red color to the blood.
- When oxygen is released from haemoglobin, the blood appears darker red.

In conclusion, the blood of Pheretima is red due to the presence of haemoglobin in the plasma.

Pheretima also known as earthworm . it is colour red because presence of haemoglobin , and to carry oxygen around the body .