Sequoyah played an important role in changing cherokee culture by a. promoting the use of us currency b. developing the cherokee alphabet c. opening trading posts and stores d. spreading christianity as a missionary

The correct answer is
B. developing the Cherokee alphabet

He made a special alphabet which was designed for the Cherokee language which made it possible for others to send written messages and read translated works and similar things. This made the Cherokee vastly superior when it came to literacy compared to other Native-American tribes.