Discussion
Hackle marks are present in :
Answer: D
Hackle marks are found in glass.
When glass breaks, the edges of the radial and concentric cracks show curved stress lines called rib marks, and fine lines at right angles to them called hackle marks. Their direction tells the examiner which side of the glass the force came from: on a radial crack the rib marks meet the side opposite the impact at right angles (the 3R rule). This helps in reconstructing break-ins and shootings through windows.
Paint, wood and steel fail differently: paint chips and flakes, wood splinters, and steel deforms or shears, so they do not show hackle marks.
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