Choose the correct option relating wavelengths of different parts of electromagnetic wave spectrum :
a. λvisible<λmicro waves<λradio waves<λx-rays
b. λradio waves>λmicro waves>λvisible>λx-rays
c. λx-rays<λmicro waves<λradio waves<λvisible
d. λvisible>λx-rays>λradio waves>λmicro waves