Prime coking coal is always blended with medium or non- coking coal before ear-bonisation

[A].	to check against its excessive swelling during heating, which may exert high pressure and damage coke oven walls.
[B].	because, it alone produces unreactive coke.
[C].	both (a) and (b).
[D].	neither (a) nor (b).

Answer: Option C

Explanation:

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