Explanation:

- Option 1: Placement agencies and management consultants

- These organizations help companies find suitable candidates by conducting searches and screenings.

- Typically used for hiring specialized or high-level positions.

- Option 2: Direct recruitment

- This involves hiring directly from the source—typically placing notices or using walk-ins.

- Companies like Roshni Limited put up a notice on the factory gate, which is a clear example of direct recruitment.

- Option 3: Labour contractors

- These are intermediaries who provide a company with manpower.

- Not suitable if the notice is placed directly by the company.

- Option 4: Advertising

- Involves spreading job vacancy information through media channels like newspapers or online platforms.

- Reaches a broader audience but not directly related to placing a notice on a factory gate.