Here is a goal: To make homemade magnetic silly putty,

Which way makes more sense to accomplish this goal?

Available options:
(A). take regular silly putty, form it into a bowl shape, put some aluminum oxide and knead till it is mixed and the texture is grainy.
(B). take regular silly putty, form it into a bowl shape, put some iron oxide and knead till it is mixed and the texture is grainy.
(B).