Question

what helped lead to war between Britain and the American colonists A. the Massachusetts military and the British army fought and Lexington B. the constitutional convention met in Philadelphia C. colonists protested British taxes in the Boston tea Party

Answer 1

It would be C, that colonists protested British taxes in the Boston Tea Party.

The fighting at Lexington was the first battle of the Revolution, so the fighting had already started.
The first Constitutional Convention met in February of 1787, which was four years after the revolution had already ended.