A machinery was purchased on 1-1-2006. It was delivered on 1-4-2006. The installation was completed on 1-7-2006. The trial run was completed on 30-9-2006 and was put to use from 1-12-2006. The effective period for calculation of depreciation for the year 2006 is

(a) 10 months

(b) 9 months

(c) 1 month

(d) 3 months