What changed people's viewpoint about the Swat Valley? The Swat turned into a big city and lost its natural beauty. Tourists flocked there, and it became too crowded. The Taliban began using it as a military base. It was no longer lush and untouched.

C. The Taliban began using it as a military base.

Explanation:

'I Am Malala' is a novel written by Malala Yousafzai. The novel is about her family and how terrorism brought trouble in their village and Yousafzai family's life.

The Swat Valley is the place where Malala and her family resided. When the Taliban invaded the Valley, they destroyed the lush greenery of the valley and made the valley their military base camp. After they destroyed the Valley, people's viewpoint changed about the Swat Valley.

Therefore, option C is correct.

a. they have shared matter.