The correct answer is: Only I is strong.
Argument I is strong because it is based on the principle of fairness. It argues that it would be unfair to promote someone simply because they have been with the company longer, if there are other employees who are more qualified for the position.
Argument II is weak because it is based on the emotional appeal of senior employees’ feelings. It argues that senior employees would feel humiliated if they were not promoted, but this does not mean that they should be promoted if they are not the most qualified for the position.
Argument III is weak because it is based on the assumption that seniority is the only measure of merit. It argues that senior employees are more experienced and must be rewarded for the same, but this does not mean that they are the most qualified for the position.
In conclusion, only Argument I is strong because it is based on the principle of fairness.