听力原文： Most people think their time problems are outer, and that they are caused by the telephone, meetings, visitors, and delayed information or decisions. Although these problems often have a bad effect on them, as when people call or drop in, we usually contribute to them. We fail to have calls screened by a skillful secretary or assistant, or we leave our door open, actually assuring constant interruptions.
In almost all cases, it is possible to influence, if not control, it usually can cause problems, such as, slowness and indecision, lack of self-discipline, the inability to delegate, or the tendency to fight fires, to act without thinking, and to jump from task to task without finishing any of them.
Time is constant that cannot be changed. The clock cannot be slowed down or speeded up. Thus we cannot manage time itself. We can only manage our activities with respect to time.
The same skills are needed as those used in managing others--the abilities to plan, organize, delegate, direct, and control. Time management is simply self-management, It is impossible to be effective in any position without controlling one's time effectively.
Successful time management does not mean working harder, but working smarter. All kinds of management skills must be used in the home and office to get most value from time. You must think ahead about what to do, and timely than others, making it get maximum results in the shortest possible period.
According to the writer, time problems ______.

A. are caused by the telephone, meetings and visitors
B. are caused by delayed information or decisions
C. can be solved by self-management
D. can't be controlled