Continuous and discontinuous variation

In a human population, eye colour shows many different shades from very light to very dark. Tongue-rolling ability is either present or absent.

Which row correctly identifies the type of variation for each characteristic?

A: eye colour – discontinuous; tongue-rolling – continuous
B: eye colour – continuous; tongue-rolling – discontinuous
C: eye colour – continuous; tongue-rolling – continuous
D: eye colour – discontinuous; tongue-rolling – discontinuous