Step 1: Understanding the Concept:
The Constitution of India contains specific provisions regarding environmental protection and conservation of forests and wildlife.
These are categorized as Directive Principles of State Policy (obligations of the state) and Fundamental Duties (obligations of the citizen).
Step 2: Detailed Explanation:
Let us review the constitutional articles listed:
1. Article 51A(g):
This article is situated within Chapter IVA ("Fundamental Duties"), which was added to the Constitution by the $42^{\text{nd}}$ Amendment Act in 1976.
It states that it shall be the duty of every citizen of India "to protect and improve the natural environment including forests, lakes, rivers and wild life, and to have compassion for living creatures."
This matches the "fundamental obligation of every citizen" mentioned in the question.
2. Article 48A:
This article belongs to the Directive Principles of State Policy (Chapter IV).
It states: "The State shall endeavour to protect and improve the environment and to safeguard the forests and wild life of the country."
This is an obligation of the government, not of individual citizens.
Step 3: Final Answer:
The citizen's obligation is enshrined in Article 51A(g).
This matches Option (A).