In the following question, out of the given four alternatives, select the alternative which best expresses the meaning of the Idiom/Phrase: "Get cracking".

Introduction / Context:
This idiom question is based on the informal phrase "Get cracking." It is commonly used in spoken English to encourage someone (or oneself) to begin doing something quickly, especially when time is limited or work is pending. Understanding this idiom helps in everyday conversations, instructions, and dialogues in examinations.

Given Data / Assumptions:

• Idiom: "Get cracking."
• Options: delay, destroy, waste time, start doing something.
• The question expects the meaning most commonly used in modern English.

Concept / Approach:
"Get cracking" means to start working on a task or activity without delay. It carries a sense of urgency and energy, as if one must get moving immediately. It is similar in meaning to "get started," "get going," or "start working quickly." Therefore, the correct answer will refer to beginning an action, not postponing, destroying, or wasting time.

Step-by-Step Solution:
Step 1: Recall typical uses: "We need to get cracking if we want to finish by tonight," or "Come on, get cracking on your homework." Step 2: Understand that in both examples, the speaker is telling someone to begin their work immediately. Step 3: Review the options and identify the one that clearly describes beginning an activity: option D, "To start doing something." Step 4: Ensure that the other options describe the opposite ideas of delay or destruction. Step 5: Choose option D as the correct meaning.

Verification / Alternative check:
Replace the idiom in a sentence: "If we want to catch the train, we must get cracking." Changing it to "we must start moving quickly" or "we must start doing something now" keeps the same sense. However, replacing it with "we must delay," "we must waste time," or "we must destroy everything" clearly changes or destroys the intended meaning, which confirms that "to start doing something" is the correct explanation.

Why Other Options Are Wrong:
Option A: "To delay little longer" is the exact opposite of the urgency implied in "get cracking." Option B: "To destroy at the end" has no relationship to starting a task or working quickly. Option C: "To waste time in waiting" also contradicts the idiom, which encourages taking action instead of wasting time.

Common Pitfalls:
Some learners may associate the word "cracking" with breaking or destroying something, so they might think the idiom is negative or violent. In reality, "get cracking" is about getting active and moving fast. It is important to learn such idioms as whole units of meaning rather than interpreting each word literally. Remember it alongside phrases like "get moving" or "get going" to reinforce the correct idea of starting an action quickly.

Final Answer:
The idiom "Get cracking" means: To start doing something (especially quickly and with energy).