Tricky problem!, but I think the answer is A.
I. Too much job security can have a negative influence on works. This is a very close and logical flow from the statement, which makes two distinct points--firstly, that Civil Service employees know how hard it is to fire them, and secondly, that because they know how hard it is to be fired they tend to loaf. Therefore, their job security causes them to underperform.
II. More government workers should be fired. This can not be confirmed in the statement, because the final sentence is unclear about which statement explains why the government is so inefficient. Is it because it costs up to $100,000 just to fire someone OR is it because people loaf due to job security? It's too ambiguous to tell.
III. Most government workers are Civil Service employees. There is no reference to number at all in the statement.
Therefore, A.