The correct answer is: Both I and II are implicit.
The statement “The organization should promote employees on the basis of merit alone and not on the basis of length of service or seniority” implies that length of service or seniority does not alone reflect merit of an employee. This is because the statement is saying that merit is the only factor that should be considered when promoting employees, and that length of service or seniority should not be considered.
The statement also implies that it is possible to determine and measure merit of an employee. This is because the statement is saying that merit is the only factor that should be considered when promoting employees, and that merit can be determined and measured.
Therefore, both assumption I and assumption II are implicit in the statement.