The correct answer is option 3, which states that Raja Rammohan Roy was responsible for all three reforms: abolition of Sati, abolition of child marriage, and widow remarriage.

Let`s analyze each option to understand why it is correct or incorrect:

Option 1 states that Raja Rammohan Roy was responsible for the abolition of Sati. This is correct because Raja Rammohan Roy played a pivotal role in advocating for the abolition of the practice of Sati, which involved the immolation or self-sacrifice of widows upon the death of their husbands.

Option 2 states that Raja Rammohan Roy was responsible for the abolition of child marriage. This is also correct because Raja Rammohan Roy campaigned against child marriage, which was a prevalent social evil during that time.

Option 3 states that Raja Rammohan Roy was responsible for widow remarriage. This is correct as well because Raja Rammohan Roy actively worked towards promoting widow remarriage, which was considered taboo in traditional Indian society.

Option 4 states that Raja Rammohan Roy was responsible for only the abolition of child marriage and widow remarriage. This is incorrect because it fails to include the reform of abolishing Sati, which was one