45.
The answer is: A
Explanation
The correct option is A: 1926.
This is because the Trade Union Act was enacted in the year 1926 and came into force on 1st June, 1927 as the Indian Trade Unions Act, 1926 (16 of 1926). The Act provides for the registration of trade unions and defines the rights and liabilities of registered trade unions.
Option B is incorrect as 1946 was the year when the Industrial Employment (Standing Orders) Act was enacted.
Option C is incorrect as 1947 was the year when the Indian Trade Union (Amendment) Act was passed.
Option D is incorrect as 1988 was the year when the Trade Unions (Amendment) Act was passed.