The ratio for the speed of the electron in the 3ʳᵈ orbit of He⁺ to the speed of the electron in the 3ʳᵈ orbit of hydrogen atom will be :___
a. 1 ∶ 1
b. 1 ∶ 2
c. 4 ∶ 1
d. 2 ∶ 1