辨认主题句: Read the following paragraph and choose the best topic sentence from the four options that follow.
My efforts to define workaholism and to distinguish workaholics from other hard workers proved difficult. While workaholics do work hard, not all hard workers are workaholics. Moonlighters, for example, may work 16 hours a day to make ends meet, but most of them will stop working when their financial circumstances permit. Accountants, too, seem to work non-stop, but many slow down after the April 15 tax deadline. Workaholics, on the other hand, always devote more time and thought to their work than their situation demands. Even in the absence of deadlines to meet, mortgages to pay, promotions to earn,or bosses to please, workaholics still work hard. What sets them apart is their attitude toward work, not the number of hours they work.