Step 1: Identify the concept being tested.
The question wants us to name and explain an external source of recruitment based on the clues in the case.
Step 2: Read the facts closely.
Veer Infrastructure needed daily wage labourers urgently for just 15 days, so the site supervisor simply put up a notice at the entrance of the construction site asking workers to report directly for the job.
Step 3: Apply the concept to the facts.
Hiring workers who walk in and apply directly at the factory or site gate, without any formal advertisement or agency involvement, is called Direct Recruitment. It is commonly used for unskilled or semi-skilled jobs that need to be filled quickly, exactly as in Veer Infrastructure's case.
Step 4: Final answer.
The external source used is Direct Recruitment, where a notice is placed at the factory or site gate and interested candidates apply and are selected on the spot, ideal for short-term, unskilled or semi-skilled requirements like the daily wage labourers Veer Infrastructure needed.