Assertion: A compass needle when placed on the magnetic north pole of the earth rotates in vertical direction.
Reason: The earth has only horizontal component of its magnetic field at the north poles.
A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true but reason is not the correct explanation of the assertion
C. f assertion is true but reason is false.
D. If the assertion and r eason both are false
