Which of the following sets of ions is colourless?

Options

A. `Zn^(2+), Cu^(2+) , Ti^(3+), Co^(2+)`
B. `Zn^(2+) , Cu^(+), Ti^(4+) , Ra^(2+)`
C. `Cr^(2+), Mn^(2+), Zn^(2+) , Ti^(4+)`
D. `Mn^(7+) , Mn^(2+), Cu^(+), V^(2+)`