Which size of angle supply 1/2" or 3/8" for lavatory faucet installation?

I do not know which size of angle supply 1/2 inch or 3/8 inch to buy to install with a new Kohler Bancroft monoblock lavatory faucet.Kohler K-10579-4-SN Bancroft Monoblock Lavatory Faucet With Escutcheon And Lever Handles. I called Kohler and they said they did not know. Any direction please. This is a remodel in a 1938 house. Thank you

3/8" compression on the outlet of the shutoff for the faucet.

ALL lavatory faucets have restricted flow so the 3/8" supplies will give more than adequate flow.