They didn't go swimming,did they?---------I saw them skate i

They didn't go swimming,did they?----＿＿＿＿＿I saw them skate in the park ,
A 、Yes,they did B、No,they didn't C、Yes,were D、No,they weren't
亲们,这题我与老师说的答案不正确伢~你们选哪个 我选了A~