The correct answer is: Enhanced employability of staff members
Rationale: 'Employability' refers to an individual's having a portfolio of skills and experience that are valuable in the labour market, thus enhancing his or her mobility (and ability to get a job outside the present employer). This is a double-edged sword for the organisation: it is socially responsible and fosters employee satisfaction but may also cause a skill drain to other organisations. You should be able to see how training contributes to the other options, and why they are benefits for the organisation.
Pitfalls: Look out for qualifier keywords like 'for an organisation' (that is, not 'for the individual'). Think carefully through 'which is the exception?' questions, too. Logically, an option may be an exception for more than one reason: in this case, because it isn't a benefit (but a drawback) or because it isn't a benefit to the organisation (but a benefit to the individual). In a well designed question, you should get the same answer either way!