What was the effect of the 'caste system' in India on people from the 'lower' castes?

They were restricted to manual labour.

The correct answer is Option 3 - They were restricted to manual labour

The caste system in India prevented people from the ‘lower’ castes from doing anything except manual labour.

The first step towards bringing about equality is, of course, ending the formal system of inequality and privileges. Social, economic and political inequalities all over the world have been protected by customs and legal systems that prohibited some sections of society from enjoying certain kinds of opportunities and rewards. Poor people were not granted the right to vote in a large number of countries. Women were not allowed to take up many professions and activities. The caste system in India prevented people from the ‘lower’ castes from doing anything except manual labour. In many countries only people from some families could occupy high positions.

Attainment of equality requires that all such restrictions or privileges should be brought to an end. Since many of these systems have the sanction of law, equality requires that the government and the law of the land should stop protecting these systems of inequality. This is what our Constitution does. The Constitution prohibits discrimination on grounds of religion, race, caste, sex or place of birth. Our Constitution also abolishes the practice of untouchability. Most modern constitutions and democratic governments have formally accepted the principle of equality and incorporated it as identical treatment by law to all citizens without any regard to their caste, race, religion or gender.