Social Legislation

Step 1: Understanding the Concept:
The question asks for the year of enactment of the first central legislation in India that restrained the practice of child marriage.
Step 2: Detailed Explanation:
The Child Marriage Restraint Act was passed in 1929. This act is popularly known as the Sarda Act, after its sponsor, Harbilas Sarda. It was a landmark piece of social legislation for its time.
The Act fixed the minimum age of marriage for girls at 14 years and for boys at 18 years. It was enacted on September 28, 1929, and came into force on April 1, 1930.
Step 3: Final Answer:
The Child Marriage Restraint Act was first enacted in 1929.