Step 1: Understanding the Concept
We need to identify the function performed by the speaker with this utterance. Step 2: Analyzing Key Phrases
The sentence begins with the phrase "I am sorry." This is the standard, explicit formula used in English to make an apology. The rest of the sentence explains the reason for the apology. Step 3: Evaluating the Options
(A) apologising: Expressing regret for having done something wrong. The phrase "I am sorry" directly performs this function. This is the correct answer.
(B) advising: Offering suggestions about the best course of action. The speaker is not giving advice.
(C) admiring: Regarding with respect or warm approval. The speaker is not expressing admiration.
(D) commanding: Giving an authoritative order. The speaker is not giving a command. Step 4: Final Answer
The phrase "I am sorry" unequivocally signals an apology. Therefore, the function of the sentence is apologising. Option (A) is correct.