What led to Syria being considered a failed state?

A.
An invasion led by U.S. forces forced Saddam Hussein out of power.

B.
King Abdullah chose 30 women to serve in the Consultative Council.

C.
A low GDP and the resulting poverty caused conflicts between its citizens.

D.
Large parts of the country came under the control of rebel groups and terrorists.

D. Large parts of the country coming under the control of rebel groups and terrorists has contributed to Syria being considered a failed state. The ongoing civil war, which began in 2011, has resulted in a humanitarian crisis, displacement of millions of people, and destruction of infrastructure. The government has lost control over significant portions of the country, and various armed groups, including ISIS, have taken control of territory. The conflict has also drawn in regional and international powers, further complicating the situation.