please help they all look the same to me also please explain why the correct answer is the answer

As the production planner for Xiangling Hu Products, Inc., you have been given a bill of material for a bracket that is made up of a base, 2 springs, and 4 clamps. The base is assembled from 1 clamp and 2 housings. Each clamp has 1 handle and 1 casting. Each housing has 2 bearings and 1 shaft. There is no inventory on hand. Click the icon to view the product structure. Your boss at Xiangling Hu Products, Inc., has just provided you with the schedule and lead times for the bracket. The unit is to be prepared in week 12. The lead times for the components are bracket (1 week), base (1 week), spring (1 week), clamp (1 week), housing (2 weeks), handle (2 weeks), casting (4 weeks), bearing (1 week), and shaft (1 week). a) Choose the correct time-phased product structure for the bracket. A. B. C. OD. handle handle handle handle clamp clamp base clamp base clamp base base casting bearing casting bearing casting bearing casting bearing LY bracket bracket bracket bracket housing spring housing spring housing spring shaft shaft shaft housing shaft spring handle clamp handle handle handle clamp clamp clamp casting casting casting casting 5 5 5 6 7 8 9 10 11 12 Time in weeks 6 7 8 9 10 11 12 Time in weeks 6 7 8 9 10 11 12 Time in weeks 5 6 7 8 9 10 11 12 Time in weeks The product structure. LT=Lead time in weeks Bracket LT=1 Base (1) Spring(2) LT=1 LT=1 Clamp(1) Housing(2) Clamp(4) LT=1 LT=2 LT=1 Handle (1) Casting(1) Shaft(1) Bearing(2) LT=1 Handle(1) Casting (1) LT=2 LT=4 LT=1 LT=2 LT=4