Assertion : If a plane glass slab is placed on the letters of different colours all the letters appear to be raised up to the same height. Reason : Different colours have different wavelengths.

• 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. If assertion is true but reason is false.
• D. If assertion is false but reason is true.