As a result of the introduction of mass transit in cities? :
a. working-class neighborhoods were broken apart.
b. different social groups no longer lived close together.
c. more mixed-use areas consisting of residences, shops, and factories emerged.
d. human resources were drawn inward toward the central city.

The correct answer is letter D. human resources were drawn inward toward the central city. As a result of the introduction of mass transit in cities, human resources were drawn inward toward the central city. It is easier to transfer from one place to the other and it's very effective most especially to working people.