Answer: B. Trap.
Answer analysis:
When discussing this question, we must first clarify what kind of routine (or mechanism) is usually used to respond to emergencies in a timely manner. Now, let's analyze each option one by one:
A. Function: The term function usually refers to the ability or role of a system, device or software. It does not specifically refer to a mechanism or program for responding to emergencies. Functions can be diverse, including but not limited to processing data, controlling devices, communicating, etc., but they are not directly equivalent to programs for responding to emergencies.
B. Trap: In programming and system design, the term "trap" usually refers to a mechanism used to capture and handle these events under specific conditions (such as hardware errors, abnormal interrupts, etc.). In an emergency, a trap can be regarded as an automatic response mechanism that can detect and immediately respond to abnormal conditions, thereby preventing serious consequences such as system crashes or data loss. This mechanism is particularly important in low-level systems (such as operating systems, hardware controls, etc.) because it can intervene and handle emergencies at the first time.
C. Program: A program is a collection of instructions designed by a computer to achieve a specific goal. Although a program can contain code to handle emergencies, it does not in itself specify a mechanism for dealing with emergencies. Programs can be complex or simple, with different contents and goals.
Taking all factors into consideration, we need to find a routine or mechanism that can "respond to emergencies in a timely manner." Of the three options, "trap" best meets this requirement. It can be automatically triggered when an emergency occurs and take appropriate measures to effectively deal with the emergency.
Therefore, the correct answer is B, trap.