What is the main idea of this reading?

Câu hỏi: Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 31 to 35.
Humans generally spent more time working than do other creatures, but there is greater variability in industriousness from one human culture to the next than is seen in subgroups of any other species. For instance, the average French worker toils for 1,646 hours a year; the average American for 1,957 hours; and the average Japanese for 2,088.
One reason for human diligence is that people, unlike animals, can often override the impulses they may feel to slow down. They can drink coffee when they might prefer a nap or flick on the air-conditioning when the heat might otherwise demand torpor. Many humans are driven to work hard by a singular desire to gather resources far beyond what is required for survival. Squirrels may collect what they need to make it through one winter but only humans worry about collect bills, retirement, or replacing their old record albums with compact discs.
Among other primates, if you don't need to travel around to get food for that day, you sit down and relax, said Dr.Frans de Waal of Emory University in Atlarita. "it's typically human to try to accumulate wealth and get more and more."
Much of the acquisitiveness is likely to be the result of cultural training. Anthropologists have found that most hunter-gatherer groups, who live day to day on the resources they can kill or forage and who stash very little away for the future generally work only three to five hours daily.
Indeed, an inborn temptation to reduce may lurk beneath even the most work-obsessed people, which could explain why sloth ranks with lust and gluttony as one of the seven deadly sins.
What is the main idea of this reading?
A. Work among Humans and Animals.
B. The Accumulation of Wealth.
C. Sloth: One of the Seven Deadly Sins.
D. Human Cultural Training.