a landscaping company Martin & Sons purchased shares of stock at 3 different times:

100 shares for 4300 on 2/1/18

300 shares for 6900 on 5/15/19

200 shares for 10000 on 1/30/20

on 6/1/21 they sold 265 shares & received gross proceeds of 13,010. if they wanted to reduce the capital gain as much as possible, which shares would they have had to specifically identify at the time of sale?