In the context of vaccination against tuberculosis, the abbreviation BCG stands for which of the following full forms?

Introduction / Context:
BCG is one of the earliest and most widely used vaccines in the world, especially in developing countries such as India, where tuberculosis remains a major public health concern. Competitive exams often ask about the full form of medical abbreviations that relate to common vaccines and diseases. This question checks whether the candidate knows what the letters B, C and G in BCG represent in the original scientific name.

Given Data / Assumptions:

- The abbreviation in the question is BCG. - The context is a vaccine used against tuberculosis. - Four possible expansions are given as options. - Only one of these matches the historically accepted full form.

Concept / Approach:
BCG stands for Bacillus Calmette Guerin, named after the French scientists Albert Calmette and Camille Guerin who developed the vaccine. The word Bacillus indicates that it is a bacterial strain. Therefore, the correct full form must preserve the names Calmette and Guerin. Options that introduce words like Cholera or Curative Gene are distractors and do not correspond to the actual history of the vaccine.

Step-by-Step Solution:
1. Recognise that BCG is used primarily as a vaccine against tuberculosis, especially in newborns. 2. Recall that the vaccine is derived from a weakened strain of Mycobacterium bovis. 3. Remember the names of the two scientists associated with the development of this vaccine, Calmette and Guerin. 4. The letter B stands for Bacillus, a type of rod shaped bacterium. 5. Combining these pieces, the expansion becomes Bacillus Calmette Guerin. 6. Among the four options, only Bacillus Calmette Guerin matches this scientific and historical explanation.

Verification / Alternative check:
This full form is consistently printed on vaccine vials, medical records and public health documents. Standard biology and medical entrance exam guides also give Bacillus Calmette Guerin as the correct expansion of BCG. No credible source uses terms such as Cholera Germ or Curative Gene in connection with BCG. Therefore, the answer can be verified quickly by cross checking with any textbook chapter on vaccines and immunisation.

Why Other Options Are Wrong:
Bacillus Cholera Germ mentions Cholera, which is caused by Vibrio cholerae, not by the bacterium associated with tuberculosis. Bacillus Curative Gene is a made up phrase that does not refer to any recognised vaccine or micro organism. Bacillus Cholera Guerin mixes the disease cholera with the scientist name Guerin and again does not match any established term. These options are included only to confuse candidates who do not fully remember the correct expansion of BCG.

Common Pitfalls:
Candidates sometimes remember only the initial letter B as Bacillus but forget the exact spelling of Calmette and Guerin. This can tempt them to choose an option that contains the word Bacillus but has wrong remaining words. Another pitfall is assuming that every abbreviation in medicine ends with the word Germ or Gene, which is not true. To avoid such errors, students should revise common vaccine abbreviations like BCG, DPT and MMR along with their full forms, target diseases and schedule of administration.

Final Answer:
In medical terminology, BCG is correctly expanded as Bacillus Calmette Guerin, the vaccine used against tuberculosis.