Which sentence uses correct punctuation?

Question

Debbie knew that studying for her test was important, consequently, she cleared her schedule for the night.

Debbie knew that studying for her test was important, consequently she cleared her schedule for the night.

Debbie knew that studying for her test was important; consequently, she cleared her schedule for the night.

Debbie knew that studying for her test was important, consequently; she cleared her schedule for the night.

Answer 1

Debbie knew that studying for her test was important; consequently, she cleared her schedule for the night.