If the coli form bacteria is present in a sample of water, then the coli-form test to be conducted is
(i) Presumptive coli-form test
(ii) Confirmed coli-form test
(iii) Completed coli-form test

A. Only (i)

B. Both (i) and (ii)

C. Both (i) and (iii)

D. All (i), (ii) and (iii)

Answer: Option D