In this idiom based question, choose the option that best explains the meaning of the expression "When it rains, it pours" used in everyday English.

Introduction / Context:
This question tests your understanding of the English idiom "When it rains, it pours". Idioms are fixed expressions whose meanings cannot always be understood merely from the individual words used. This specific idiom is commonly used in everyday conversation to describe a situation where misfortunes or problems do not come one by one, but many together or in quick succession.

Given Data / Assumptions:

• Idiom: "When it rains, it pours".
• Options describe different interpretations of difficulties and timing.
• We assume the idiom refers to the way events often cluster, especially negative ones.
• We need the option that correctly captures the idea that one problem is quickly followed by many others.

Concept / Approach:
Literally, rain can start as a light drizzle and then suddenly become a heavy downpour. Figuratively, the idiom suggests that when trouble or bad luck starts, it often seems to come all at once or repeatedly. The correct explanation should mention this piling up or repetition of negative events. We must distinguish this from general statements about bad times or being unprepared, which are similar but not precise matches.

Step-by-Step Solution:
Step 1: Recall the general meaning of the idiom. It is usually said when several bad things happen at almost the same time. For example, losing a job, then falling ill, then facing a financial problem in one short period. Step 2: Examine option A, which speaks of "getting much less than what one expected". That is about disappointment, not about many bad events clustering together. Step 3: Option B says "calamity always occurs in bad times". This is vague and does not describe repeated or multiple problems, only that bad events happen when things are already bad. Step 4: Option C states "you always fall into trouble when you are least prepared". This focuses on being unprepared rather than on the number or frequency of problems. Step 5: Option D says "When something bad occurs, it usually occurs more than once". This directly expresses the idea that problems rarely appear alone, but instead come in clusters, which is the core meaning of the idiom.

Verification / Alternative check:
Think of an example. Suppose someone says, "First my car broke down, then my laptop crashed, and now I have caught a cold. When it rains, it pours." They clearly mean that one problem followed another and another. The emphasis is on multiple issues happening together or very close in time. None of the options except D emphasises this repetition. Therefore, option D is the exact match.

Why Other Options Are Wrong:
Option A describes disappointment in expectations, which has nothing to do with a series of misfortunes.

Option B talks about calamity in bad times but does not emphasise multiple problems arriving together.

Option C focuses on preparedness and timing, suggesting trouble comes when you are least prepared, but again does not capture the piling up effect.

Common Pitfalls:
Learners sometimes get attracted to options that mention "bad times" or "calamity" in general, since the idiom clearly refers to negative events. However, idioms often carry a more specific nuance. Here, the key nuance is that difficulties come in bunches rather than in isolation. In idiom questions, always identify the distinctive twist of meaning rather than only the general positive or negative tone.

Final Answer:
The idiom means that when something bad happens, more bad things tend to follow, so the correct option is: "When something bad occurs, it usually occurs more than once".