Industrial workers often labored:

A. for high wages.
B. under ideal conditions.
C. in well-ventilated factories.
D. with unsafe machinery.

The correct answer is D. with unsafe machinery.

During the Industrial Revolution, industrial workers often had to work with unsafe machinery. To arrive at this answer, we can eliminate the other options based on historical context and common knowledge.

Option A states that industrial workers labored for high wages, but this is generally not true during the early years of the Industrial Revolution. Many workers were paid low wages, especially in the beginning stages of industrialization when labor laws were not yet in place.

Option B suggests that workers labored under ideal conditions. However, this is not the case. In fact, working conditions during the Industrial Revolution were often harsh and dangerous. Workers faced long hours, low pay, lack of breaks, and unsanitary conditions.

Option C mentions well-ventilated factories. While ventilation did improve over time, it was still insufficient in many factories during the early stages of industrialization. Poor ventilation meant that workers were exposed to harmful fumes, dust, and other pollutants.

This leaves us with the correct answer, D. with unsafe machinery. During the Industrial Revolution, safety regulations were lacking, and workers often had to operate dangerous machinery without proper safeguards. This led to frequent accidents, injuries, and even deaths in industrial workplaces.

In summary, industrial workers during the Industrial Revolution labored with unsafe machinery, which made their working conditions perilous and risky.