You Want to Derive the Gender from a Firstname, How

You want to derive the gender from a firstname, how would you do this?

A) Use a reference table with the firstname as the valid column and the gender in the second column. Then choose to Replace Reference Table Matches with Valid Values when applying the reference table in a strategy in the Standardizer. Use the firstname as input.
B) Use a reference table with the gender as the valid column and the firstname in next column. Then choose to Replace Reference Table Matches with Valid Values when applying the reference table in a strategy in the Standardizer. Use the firstname as input.
C) Use a decision and create an If then else rule eg: If fname = 'Jennifer' then gender: = 'F' Endif
D) Then choose to Replace Reference Table Matches with Custom Strings when applying the reference table in a strategy in the Standardizer. Use the firstname as input.