Answer: developing international cartels
Step-by-step explanation:
The business practices that were employed by the titans of industry in the late 1800s include the building of monopolies, establishing trusts and the standardizing of production.
This led to the growth of the industries. While the owners of the businesses got richer, their employees were bit treated well and they were paid unfairly for the services that they rendered.
It should be noted that developing international cartels wasn't among the practices that they used. Therefore, the correct option is D.