How do I create a drop down list for selection.

If I want the following in my drop down lists:-
For Column C Row 3 to 7
89901 Blue Strips 1"
89902 Blue Strips 2"
90001 Red Strips 1"
90002 Red Strips 2"

and Column E Row 3 to 7

S0001 XSmall
S0002 Small
S0003 Large
S0004 XLarge

Say if I select 89902 Blue Strips 2" and S0003 Large from Column C and E
drop down lists and only want 89902 and S0003 to appear in the respective
columns.