Match the casting defects (Group A) with the probable causes (Group B):
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Group A
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Group B
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P: Hot tears
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1. Improper fusion of two streams of liquid metal
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Q: Shrinkage
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2. Lows permeability of the sand mould
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R: Blow holes
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3. Volumetric contraction both in liquid and solid stage
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S: Cold shut
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4. Differential cooling rate
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(a) P-1, Q-2, R-2, S-4
(b) P-4, Q-3, R-2, S-1
(c) P-3, Q-4, R-2, S-1
(d) P-1, Q-2, R-4, S-3