Sorting Materials and Groups

Boojho found a bag containing the following materials
(i) Mirror
(ii) Paper stained with oil
(iii) Magnet
(iv) Glass spectacles
Help Boojho in finding out the material(s) which is/are opaque.
(a) (i) only (b) (iv) only
(c) (i) and (iii) (d) (ii) and (iv)