In the context of Indian defence and research organisations, DRDL is an abbreviation that stands for which of the following?

Introduction / Context:
This general knowledge question asks about the full form of the abbreviation DRDL, which appears in the names of Indian defence research establishments. Acronyms and their expansions for major organisations like DRDO, ISRO and others are common items in competitive exams. Recognising the correct expansion of DRDL shows familiarity with India's defence and research infrastructure.

Given Data / Assumptions:

• The acronym to be expanded is DRDL.
• Options provide different possible expansions involving research and laboratories.
• We assume the question refers to the well known Indian defence establishment under DRDO.

Concept / Approach:
DRDL stands for Defence Research and Development Laboratory. It is a key laboratory of the Defence Research and Development Organisation (DRDO) in India, mainly associated with missile and aerospace related research. Other expansions in the options are either grammatically awkward or not used in official names. By recalling the correct association of DRDL with defence research, we can choose the right answer.

Step-by-Step Solution:
Start with option A: Defence Research and Development Laboratory. This fits the pattern used by DRDO for its laboratories, where each laboratory name clearly states its role in defence research and development. Option B: Department of Research and Development Laboratory, sounds forced and redundant. Official Indian organisations do not commonly use this exact phrase for DRDL. Option C: Differential Research and Documentation Laboratory, introduces words like differential and documentation that do not match the known goals of DRDL in missile and defence technology. Option D: None of the above, can only be correct if all other options are incorrect, which is not the case here. Therefore, the correct full form of DRDL is Defence Research and Development Laboratory.

Verification / Alternative check:
You can verify this from standard GK reference books that list Indian space and defence organisations. DRDO is expanded as Defence Research and Development Organisation, and DRDL as Defence Research and Development Laboratory, often located at Hyderabad. This consistency in naming reinforces that option A is the correct expansion. The other expansions, besides being uncommon, do not appear in official lists of Indian defence labs.

Why Other Options Are Wrong:
Option B introduces the phrase Department of, which does not align with DRDL, as DRDL is not a department but a laboratory. Option C uses Differential and Documentation, which are out of place in the context of missile and defence research and do not correspond to any widely known laboratory name. Option D, None of the above, is incorrect because a correct expansion is available among the options, namely option A.

Common Pitfalls:
Some candidates confuse DRDL with DRDO and may think DRDL is another form of the same acronym. Others may be tempted by long, complicated sounding names without considering whether they reflect real organisations. A good strategy is to remember that DRDO covers the organisation and DRDL refers to one of its laboratories, both sharing the Defence Research and Development wording with a different last letter for Organisation and Laboratory respectively.

Final Answer:
DRDL stands for Defence Research and Development Laboratory, so option A is correct.