Which of the following statements is correct about using the method of transforming projection planes to find the inclination angle of the general position line to the projection plane?
选项：

A:When calculating α, the new projection axis (O1X1) should be placed parallel to ab;
B:When calculating α, the new projection axis (O1X1) should be placed parallel to a'b';
C:When calculating β, the new projection axis (O1X1) should be placed parallel to ab;
D:When calculating β, the new projection axis (O1X1) should be placed parallel to a'b'