Topic: Adverb (ক্রিয়াবিশেষণ),

Best Answer Explained in Below-:

The correct answer to the sentence 'If Ruby is heated it --- temporarily loses its colour.' is D) often, and this choice can be understood by analyzing the context and grammatical structure of the sentence.

In the conditional statement, “If Ruby is heated,” we are discussing a scenario that describes a common or habitual outcome, as indicated by the use of "often." This suggests that the temporary loss of color when Ruby is heated is a frequent occurrence, rather than a definitive or guaranteed result, which would be implied by "will."

The word "do" (A) would not fit grammatically, as it doesn't make sense for this context. "Has" (C) suggests possession rather than action and would not convey the temporary status of the color change. Therefore, "often" effectively communicates that this phenomenon is something that regularly happens under the specified condition.

By using “often,” the sentence captures the idea that heating Ruby commonly results in a temporary color change, emphasizing the behavior of the material rather than presenting it as an absolute certainty.