单项选择题

A.片厚则涡流损耗大,片薄则涡流损耗小
B.片厚则涡流损耗大,片薄则涡流损耗大
C.片厚则涡流损耗小,片薄则涡流损耗小
D.片厚则涡流损耗小,片薄则涡流损耗大