Poaching in Africa has been the greatest threat to wildlife for decades, and though measures, such as awareness programs and establishing stricter laws, were being taken years ago, increasing global demand for animal horns, skins, and hides are putting wild animals under the threat of extinction.

A) though measures, such as awareness programs and establishing stricter laws, were being taken years ago, increasing global demand for animal horns, skins, and hides are

B) though such measures as awareness programs and establishing stricter laws were taken years ago, increasing global demand for animals with horns, skins, and hides are

C) though measures like starting awareness programs and establishing stricter laws have been taken years ago, increasing global demand for animal horns, skins, and hides is

D) with measures, such as awareness programs and stricter laws, taken years ago, increasing global demand for animal horns, skins, and hides is

E) though measures, such as awareness programs and stricter laws, have been taken years ago, increasing global demand for animal horns, skins, and hides is

The OA is E.

I need some help here. I don't know why E is the right option. How can I discard the rest of the options?