Which of the following is an internal source of recruitment?

Transfer

The correct answer is option 1- Transfer.

Other options are external sources of recruitment.

Internal Sources: It means recruitment from within the enterprise. There are two important sources of internal recruitment, namely, transfers and promotions, which are discussed below:
(i) Transfers: It involves shifting of an employee from one job to another, one department to another or from one shift to another, without a substantive change in the responsibilities and status of the employee.
(ii) Promotions: Business enterprises generally follow the practice of filling higher jobs by promoting employees from lower jobs. Promotion leads to shifting an employee to a higher position, carrying higher responsibilities, facilities, status and pay. Promotion is a vertical shifting of employees. This practice helps to improve the motivation.