The construction workers are considered as :

The correct answer is option (3) : Casual wage labourers

The construction workers are known as casual wage labourers; they account for 30 percent of India's workforce.

Workers who own and operate an enterprise to earn their livelihood are known as self employed. Thus the cement shop owner is self-employed. About 52 percent workforce in India belongs to this category. When a worker is engaged by someone or an enterprise and paid his or her wages on a regular basis, they are known as regular salaried employees.