What is the central idea of the paragraph?
Another thing that changed very little in the years
between the wars was the means of obtaining military
intelligence. Although the use of photography and the
telegraph brought some technological advances, the craft
of spying on the enemy's army still relied on fieldwork.
For the most part, intelligence was gathered in simple
ways. Prisoners of war and deserters were interrogated.
The Union army was always interested in hearing what
runaway slaves had to report.
- The Dark Game,
Paul Janeczko
O Technological advances made a difference
craft of spying.
Interrogations are an important way to obtain
information.
The Union army gathered stories from runaway
slaves.
Intelligence was often gathered in simple ways,
such as relying on fieldwork.

The central idea in the passage is The Union army gathered stories from runaway slaves. Intelligence was often gathered in simple ways, such as relying on fieldwork.

What is a central idea?

This refers to the central unifying element of a story.

In the excerpt, the central idea is about the army and the runaway slaves.

The correct answer is option D.