The correct answer to this open question is the following.
Although there are no options attached, we can say the following.
Why is eastern Ukraine considered to be one of the most heavily militarized areas in the world?
Answer:
Eastern Ukraine is considered to be one of the most heavily militarized areas in the world due to its conflict with Russia that started in 2014 and has increased tensions to the point of having more than 1.5 million people displaced from the region and unfortunately, approximately 10,000 civilians have been killed, as part of the collateral damage.
The conflict lived its worst moments in 2018 when Russia order air raids over the Ukrainian region.
