Assertion: Small disc-shaped structures at the surface of the centromeres are called kinetochores.
Reason: Kinetochores serve as the sites of attachement of spindle fibres to the centreomeres.

Options

A. If both assertion and reason are true and reason is the correct explantion of assertion
B. If both assertion and reason are true but reason is not the correct explnantion of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

B

Explanation

In metaphase, discontinous fibres radiate out from two spindle poles and get connected to the disc shaped structure at the surface of the centroemre called kinetochores. These are called chormose fibres or tractile fibrils. A kinetochore is a complex protein sturcutre that is analogous to a ring for the mictrotubule hook, it is the point where microtubules attach themselves to the chromosome.