Garbage in, Garbage out

The steps required for conversion of kitchen garbage into
manure are given below in a jumbled form.
(i) Put garbage in a pit
(ii) Cover the bottom of the pit with sand
(iii) Cover the pit loosely with a gunny bag or grass
(iv) Add worms
Which of the following shows the correct sequence of the above
steps?
(a) (ii); (i); (iii); (iv) (b) (i); (ii); (iii); (iv)
(c) (ii); (iv); (i); (iii) (d) (iv); (i); (ii); (iii)