Explanation:

The Maternity Benefit Act, 1961 is a legislation that protects the employment of women at the time of her maternity. It entitles women employees of 'maternity benefit' which is fully paid wages during the absence from work and to take care of her child.

• Every woman entitled to maternity benefit under this Act shall also be entitled to receive from her employer a medical bonus of one thousand rupees, if no pre-natal confinement and post-natal care is provided for by the employer free of charge.

• The Central Government may before every three years, by notification in the Official Gazette, increase the amount of medical bonus subject to the maximum of twenty thousand rupees.

Note: Right now a woman is entitled to a medical bonus of Rs 3,500/- if pre-natal confinement and post- natal care is not provided by the employer free of charge. 

Hence option 4th is correct.