Statement-1 : Electromagnetic waves with frequencies smaller than the critical frequency of ionosphere cannot be used for communications using sky wave propagation.
Statement-2: The refractive index of the ionosphere becomes very high for frequencies higher than the critical frequency.

Options

A. If both Assertion & 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 expalanation of the assertion
C. if assertion is true , but reason is false
D. both assertion and reason are false statements.

Explanation

If frequencies of the waves are less thaat of the critical frequency. They will be reflected back as the ionosphere has refractive index less than free space. This is the principle, of sky wave porpagation.
Theforem the assertion is wrong.
The statement given in the reason that the refactive index. becomes high is corect. But the reason given is not true for all assertion.
Assertion is wrong. Reason-statement is correct. But not hte reason. We have to put (e) as this is a rare case where teh assertion itself is wrong.