How can I populate multiple custom fields based on user selection on one custom field

[Shrups]

Hi,

How can we achieve the below ? 

Let's say we have 5 custom fields. CF1 options = A, B, C, D, E. If user selects 'A',

CF2 should show only A1, A2, A3

CF3 should show A4, A5,A6

CF4 should show A7...A15

Similarly, if user selects 'B' on CF1, CF2 should show only B1,B2,B3,

CF3 should show only B4,B5,B6

CF4 will show only B7, B8,B9. 

Note that CF1 will have more than 2000 values. What is the best way to do this?