The correct answer is D.
The first two statements represent factors that would cause construction of homes to decrease, not increase.
Statement C is also incorrect because many African-Americans were denied mortgages after World War II. Banks would refuse to give low cost mortgages to African-Americans even though they served in the US military. Along with this, African-Americans were also excluded from many suburban neighborhoods, showing that they were not the target audience of this construction boom.
This shows that D is the correct answer. This makes sense, as the Great Depression was an era in which hundreds of thousands of Americans became homeless and could not afford to buy a new house. Since not many people were able to afford new homes, they were not built.