Step 1: Concept
The Drugs and Magic Remedies (Objectionable Advertisements) Act, 1954, generally prohibits advertising drugs for certain diseases and conditions to prevent self-medication.
Step 2: Meaning
However, certain classes of drugs are exempted from these strict prohibitions to support public health initiatives.
Step 3: Analysis
Advertisements related to the prevention of conception (contraceptives) are permitted under the law to promote family planning and reproductive health.
Step 4: Conclusion
Hence, advertising an oral contraceptive is legally allowed.
Final Answer: (C)