Choose the option that best expresses the meaning of the idiom "Put two and two together" as used in careful logical reasoning.

Introduction / Context:
This question examines your understanding of a common English idiom. Idioms are expressions whose meanings cannot be understood simply by translating each individual word. The phrase "put two and two together" is widely used in spoken and written English, especially when someone reaches a conclusion based on information they already have.

Given Data / Assumptions:

• The idiom presented is "Put two and two together".
• The options describe different possible meanings: being bad at mathematics, having poor financial condition, reasoning logically, and forgetting something.
• We assume that the idiom is used in the standard sense in conversational English.
• The task is to match the idiom to its most accepted figurative meaning.

Concept / Approach:
Idioms often come from simple images, but their figurative meanings are fixed. The image here is of basic arithmetic, where putting two and two together gives four. By extension, it suggests making a simple logical connection between different pieces of information. We need to choose the option that reflects this idea of drawing a sensible conclusion from available facts.

Step-by-Step Solution:
Step 1: Recall the standard meaning of "put two and two together". It is used when someone looks at different clues and reaches an obvious conclusion.Step 2: Match this with the option "Reason logically". When a person reasons logically, they connect facts in a sensible way, just like combining simple numbers.Step 3: Consider "Bad at mathematics". This would be the literal opposite image of doing arithmetic correctly, but the idiom does not carry this meaning in real usage.Step 4: Consider "Poor financial condition". There is no link between the idiom and a person's money situation, so this option is not relevant.Step 5: Consider "Forget something". Forgetting is about losing information, whereas the idiom is about connecting information.Step 6: Therefore, "Reason logically" best captures the figurative sense of the idiom.

Verification / Alternative check:
Look at example sentences: "He saw her car outside the house and put two and two together", meaning he realised she must be inside. Another example is "From their behaviour, we can put two and two together and guess that they are planning a surprise". In both examples, the idiom clearly indicates drawing a conclusion from evidence, not doing arithmetic, being poor, or forgetting something. This confirms that the correct interpretation is logical reasoning.

Why Other Options Are Wrong:
Option A, "Bad at mathematics", is a literal misreading of the numbers in the idiom. The expression is not about arithmetic skill at all.
Option B, "Poor financial condition", wrongly associates "two and two" with money or budget calculations, which is not part of the idiom's meaning.
Option D, "Forget something", is unrelated because the idiom deals with combining information, not losing it.

Common Pitfalls:
Some candidates overthink idioms and try to interpret them literally, or guess based on a single word such as "two". Others may confuse this idiom with expressions about being "slow at sums" or money management. The safest method is to build familiarity with common idioms through reading and practice so that you can recall their meanings instantly in the exam.

Final Answer:
The idiom "Put two and two together" means "reason logically", so option C is correct.