Why is Dharma Sabha an example of counter movement?

The correct answer is Option (2) → It defended the practice of Sati and refused to bring in any change.

Option (1) It defended the right of older women to practice Sati. — Incorrect. It defended sati itself, not a right of older women.

Option (2) It defended the practice of Sati and refused to bring in any change. — Correct. A social movement works to bring about social change; a counter movement arises against it in defence of the status quo, the existing state of things. When Raja Rammohun Roy campaigned against sati and formed the Brahmo Samaj, the defenders of sati formed the Dharma Sabha and petitioned the British not to make any law against sati. It wanted the old custom kept as it was and resisted the change the reformers sought, which is why it is a counter movement.

Option (3) It attacked Sati but not the problem of polygamy. — Incorrect. Attacking sati was the work of the reformers.

Option (4) It was against mass mobilization but wanted new rules to abolish Sati. — Incorrect. It wanted no law against sati.