Question

finding bombs in germany
during world war ii, american and british forces dropped millions of tons of bombs on german cities. nearly ten percent of the bombs never exploded. the war ended in 1945, but more than two thousand tons of unexploded bombs are still found in germany each year. before any construction project is undertaken, the site must be checked for unexploded bombs. buried bombs are often discovered. for this reason, germany has a special force of firefighters and police officers, called the kmbd, to defuse and remove these bombs. even though the war has been over for seven decades, the kmbd is one of the busiest bomb squads on the planet.
what is the main, or central, idea of the passage?
because there are so many unexploded bombs in germany, the country has a special force trained to defuse them.
because there is so much construction in germany, the country has a special force trained to defuse bombs.
almost ten percent of the bombs dropped on germany during world war ii never exploded.

Explanation:

The passage first establishes that WWII left millions of unexploded bombs in Germany, with thousands still found yearly, then explains that this ongoing hazard led to the creation of the special KMBD force to defuse them. The other options are either supporting details (the 10% statistic) or incorrect (construction is a context for discovery, not the reason for the force).

Answer:

Because there are so many unexploded bombs in Germany, the country has a special force trained to defuse them.