Study the given diagram carefully and answer the question that follows. The numbers in different sections indicate the number of persons. (NOTE: You have to take the given data to be true even if they seem to be at variance from commonly known facts.)

How many young adults are entrepreneurs?

The correct option is 21.

To find the number of young adults who are entrepreneurs, we need to analyze the overlapping regions in the Venn diagram. The diagram contains three circles representing different groups:
1. Men (the top circle)
2. Entrepreneurs (the bottom-left circle)
3. Young Adults (the right circle)

Let us identify the numbers representing the various sections in the diagram:
- 19: Men who are neither young adults nor entrepreneurs.
- 12: Young adults who are neither men nor entrepreneurs.
- 2: Entrepreneurs who are neither men nor young adults.
- 14: Persons who are both men and young adults, but not entrepreneurs.
- 8: Persons who are both men and entrepreneurs, but not young adults.
- 3: Persons who are both young adults and entrepreneurs, but not men.
- 18: Persons who belong to all three categories (men, young adults, and entrepreneurs).

The question asks for the total number of young adults who are entrepreneurs. This is represented by the entire region of intersection between the Young Adults circle and the Entrepreneurs circle. This intersection consists of two parts:
- Young adults who are entrepreneurs but not men: 3
- Young adults who are entrepreneurs and also men: 18

To find the total, we add these two values together:

$18+3=21$

Therefore, there are 21 young adults who are entrepreneurs.