The correct answer is D) Bright yellow or orange. During normal boiler operations, the flame at the end farthest from the burner should appear as a bright yellow or orange color. This is in accordance with industry standards and best practices for the proper combustion and operation of a boiler system. The other answer choices are incorrect because: A) Dark brown would indicate incomplete combustion, B) Dazzling white is not the expected color, and C) Light brown haze would suggest improper air-fuel mixture or other operational issues.