Which of the following was not included in Adam Smith's theory of wealth accumulation?

I believe the answer is: When labor tasks become divided.

Division of labor indeed is considered to be an important component for Adam Smith's free market theory. But, Adam Smith is not the one that popularized the concept of division of labor for wealth accumulation, since its already exist since ancient Greek. Adam smith's theory for wealth accumulation focused on providing a matching supply for the existing demands in the market.

The answer to this question is usually,

When labor tasks become divided, productivity increases. Adam Smith contained all his ideas in his "Wealth of Nations". The most important aspect of this book was a Theory of Economic Development