In angiosperms, all the four microspore tetrads are covered by a layer that is formed by.

The correct option is A

Callose

The correct option is A.

Explanation of the correct option:

Option A:

1. One of the plant polysaccharides is callose.
2. It is known for its quick degradation properties, high impermeability, and rapid synthesis.
3. Callose forms a layer around the reproducing spores in angiosperms, and it seals the cells undergoing meiosis from one another.
4. Hence, it prevents the dividing cells from cohesion and fusion with each other.
5. The spores are released at once when the callose layer is destroyed.

Explanation of the incorrect options:

Option B:

1. Pectose is another polysaccharide found in the cell walls of unripe fruit.
2. The pectose is converted to pectin via enzymatic activity.
3. Pectose helps in the DNA repair process and also holds the cells together via cell adhesion.
4. It also provides wall hydration.

Option C:

1. Sporopollenin is a biopolymer found on the outer surface of pollen grains.
2. It is a very resistant chemical.
3. It contains long-chain fatty acids, phenylpropanoids, phenolics, carotenoids, xanthophyll, etc.
4. Hence, it helps the pollen in surviving extremely unfavorable conditions and protects it from high temperature, acids, alkali, etc.

Option D:

1. Cellulose is a polysaccharide found in plant cell walls.
2. Cellulose is made up of the polymer of β-1,4 linked d-glucose units.
3. It is a tough fibrous molecule that keeps the plant cell structure sturdy.
4. It protects the plant cell from turgor pressure.

Final answer: In angiosperms, all the four microspore tetrads are covered by a layer that is formed by Callose.