When sodium bicarbonate is heated strongly for calcined in a kiln, it form
Correct option is B. $$Na_2CO_3$$
On heating sodium bicarbonate strongly it decomposes to give carbon dioxide, water vapour, and sodium carbonate.
Reaction :
$$\mathrm{2NaHCO_3(s) \rightarrow Na_2CO_3(s) + CO_2(g) + H_2O(g)}$$
Hence, Option "B" is the correct answer.