What happened in iraq after the united states invaded in 2003?
a. iraq quickly became a peaceful democracy.
b. the iraqis failed to adopt a new constitution within a couple of years.
c. sectarian violence increased dramatically.
d. a new parliament and president were rapidly elected.

c. Sectarian violence increased dramatically.

Explanation:

The disappearence of a strong center with the demise of the Saddam Hussein´s regime created a power vacuum in Iraq. Sectarian violence and warfare spread throughout the country,  many old grievances and conflicts that had been dormant during the Hussein dictatorship resurfaced. One of the main conflicts of post-war Iraq is the clash of Sunnis and Shiias. Shiias are the majority. In this situation, Iran has managed to increase its influence over its neighbor. 16 years after the US-led invasion, Iraq is not a  fully stable country.

they united the colonies in their fight against the british.