What is the answer to this

What type of sentence has at least one independent and one dependent clause

Ahistorian has discovered a letter written by an early roman emperor. she translates the letter and discovers that it contains orders to a general before a battle. she works to determine when the letter was written to figure out which battle the letter references.the historian in the passage is most clearly demonstrating which historical thinking skill? a. identifying causes and historical contextb. thinking chronologicallyc. making and evaluating arguments and interpretationsd. analyzing historical sources

Why did the british government relax rules regulate trade for the american colonies in the late 1600s?