which workpiece has a greater spring back effec on bending?

[MechaMZ]

which workpiece has a greater spring back effec on bending?

http://img94.imageshack.us/img94/6549/springback.jpg

Should be A or B?
How do i figure it out? by using spring estimation equation?

thank you

[MechaMZ]

any idea? i think should be B, because it is thicker at the bend area, isn't?