Innermost region of flame having the temperature A. highest B. lowest C. medium D. high to low

The innermost region of a flame has the highest temperature. This is because the fuel and oxygen are mixed together in this region and the chemical reaction that produces the flame is most intense. The temperature of the flame decreases as you move away from the center, due to the loss of heat to the surrounding air.

Option A is the correct answer.

Option B is incorrect because the innermost region of the flame has the highest temperature.

Option C is incorrect because the innermost region of the flame has the highest temperature, not the medium temperature.

Option D is incorrect because the temperature of the flame decreases as you move away from the center, not increases.