This question assesses the knowledge of fixed expressions in English, which are phrases with meanings that cannot be inferred from the literal definitions of the words. The correct answer is B, 'Break the ice', which is a fixed expression meaning to initiate conversation in a social setting. Option A, 'Break a leg', is a fixed expression but is used to wish someone good luck, not to initiate conversation. Options C and D are not fixed expressions; their meanings can be inferred from the literal definitions of the words.