Answer: B. Impact B happened before impact X.
Step-by-step explanation:
Radial fractures are the fractures which radiate out from the point of impact in the form of radiating lines. It originates on the opposite side of the impact. The original radial fracture will appear in a wavy line and the extensions of such fractures appear straight.
During the formation of fracture on the glass with multiple impacts. The fracture lines formed by the second impact stops where the line of fracture meet the fracture line caused by the first impact. These lines of fractures can be interpreted to determine that which impacted happened first.
In the given situation, radial cracks from impact X stops at the cracks of impact B. This indicates that impact B happened before impact X.