If a=b and b=c then what? - a funny

This is too rich not to share (it's hard to believe that this really happened):

A fellow designer received a "multiple choice" question from a SME. I've changed the content to protect the innocent, but you'll see what I mean.

Question:
Why is the sky blue?

a) Because "blue" light has the shortest wavelength and there is a lot of it, so that's what our eye perceives

b) Because the blue is reflected from the oceans and lakes

c) Only a

d) Only b

e) a and b