Polytene chromosomes may be defined as the giant chromosomes that contain alternate dark and light bands when view under the microscope. These chromosomes are found in the salivary gland of Drosophila.
These glands are functionally highly active and contain thousand of DNA strands. These chromosomes are aligned parallel with each other as the replication is normal but the cells are unable to separate and fails to undergo the process of cytokinesis.
A is the correct answer because paleomagnetism is the record of Earth's strength and direction in it's magnetic field. It helps us in the knowledge of evolution.
