What is the most effective way to combine sentences 17 and 18?

Group of answer choices

The colonists refused to buy stamps and they were determined to get the Stamp Act repealed.

The colonists refused to buy stamps, and they were determined to get the Stamp Act repealed.

The colonists refused to buy stamps, and were determined to get the Stamp Act repealed.

The colonists refused to buy stamps, were determined to get the Stamp Act repealed.