Step 1: Understanding the Concept:
The question asks to identify the specific article and clause of the Indian Constitution that provides the fundamental right to equality of opportunity in public employment.
Step 2: Detailed Explanation:
Article 16 (1): This clause explicitly states, "There shall be equality of opportunity for all citizens in matters relating to employment or appointment to any office under the State." This is the direct provision guaranteeing this right.
Article 22 (1): This article provides protection against arrest and detention. It is not related to employment.
Article 16 (4): This is an enabling provision that allows the State to make reservations for backward classes. It is an exception to the general rule of equality in Article 16(1), not the source of the general guarantee itself.
Article 20 (1): This article provides protection against ex post facto criminal laws. It is not related to employment.
Step 3: Final Answer:
Article 16(1) is the specific constitutional provision that guarantees equality of opportunity in matters of public employment.