Okay, the mission statement. I hardly think "Improve the safety conditions around work stations for staff" is a suitable workplace mission statement. You don't "aim" to create a safe workplace - you just do it because it's the law. If I walked into a company and saw that mission statement on the wall, I would walk out straight away. No company should need to create a mission statement to improve safety.
Another option there is 'reduce the number of supervisors' which I think is incorrect as supervisors are there for a reason, and removing them would suggest you're going to remove the people below them as well - suggesting downsizing, which you wouldn't find in a mission statement.
That leaves 'Reduce the number of help desk calls' and 'Strengthen the company's reputation with clients'. Now, I answered the latter however I now think the former is the correct answer. In your typical multiple choice question, they will give you 4 choices, two or three of which are possibly correct, and one or two which are just not correct at all. Three of the options were related to internal operations of the company, with only one relating to external operations (the one which refers to clients). So I'm inclined to think that 3.B. is the correct answer with 3.C. being the next best one. It all depends on your definition of "-workplace- mission statement".