In this vocabulary based fill in the blank question, select the most appropriate word to complete the sentence: "To ensure a _________ reply, please include all pertinent details in your email."

Introduction / Context:
This is a vocabulary driven fill in the blank question. You are asked to choose the most appropriate adjective to complete the sentence: "To ensure a _________ reply, please include all pertinent details in your email." Such questions test your understanding of common collocations, that is, natural combinations of words that native speakers frequently use together in everyday and formal communication.

Given Data / Assumptions:

• The base sentence is: "To ensure a _________ reply, please include all pertinent details in your email."
• The options are: "prompt", "efficient", "tardy", and "strange".
• The context is email communication and the aim is to get a certain kind of reply.
• The phrase "please include all pertinent details" suggests that giving complete information will help the reply to be quick and appropriate.

Concept / Approach:
When reading the sentence, you should recognise the common expression "prompt reply". In English, we often say "Thank you for your prompt reply" to mean a quick, timely response. The verb "ensure" plus the object "reply" fits naturally with "prompt" as an adjective. While "efficient" is also a positive word, it typically describes processes, systems or people's way of working, not the speed of a reply in this particular phrase. "Tardy" means late, and "strange" makes no sense here. Therefore, "prompt" is the best fit.

Step-by-Step Solution:
Step 1: Understand the intention of the sentence: the writer wants the reply to be of a certain desirable quality.Step 2: Notice the hint "please include all pertinent details", which implies that complete information helps the recipient answer quickly.Step 3: Recall common collocations such as "prompt reply" meaning "quick response".Step 4: Check whether "efficient reply" is equally natural; while possible, it is much less common than "prompt reply" in standard usage.Step 5: Eliminate negative or irrelevant adjectives like "tardy" (late) and "strange" (odd) and choose "prompt" as the most idiomatic and context friendly option.

Verification / Alternative check:
To verify, insert each option into the sentence. "To ensure a prompt reply, please include all pertinent details in your email" is a sentence that you might see in real professional communication. "To ensure an efficient reply" sounds slightly awkward; we more often talk about an efficient process, system or service rather than an "efficient reply". "Tardy reply" would be a negative expression and does not match the intention of the sentence. "Strange reply" is unrelated to the idea of including details for better service. This comparison confirms that "prompt" is the best choice.

Why Other Options Are Wrong:
"Efficient" describes the effectiveness and lack of waste in a process, but is not the usual adjective in this fixed phrase. "Tardy" means late or delayed, which is the opposite of what the sender wants to ensure. "Strange" refers to something unusual or odd and has no logical connection to including pertinent details. These options either clash with the positive intention of the sentence or fail to form a natural expression in English.

Common Pitfalls:
One common mistake is to pick any positive word without considering collocations. Another is to be distracted by the formal tone of "efficient" and think that formal equals correct. In reality, exam setters often target these subtle usage patterns. Whenever you see the word "reply", train yourself to recall common partners like "prompt reply" or "quick reply". This habit will help you answer similar questions quickly and accurately.

Final Answer:
The correct option is prompt, giving the natural and widely used expression "To ensure a prompt reply, please include all pertinent details in your email."