Here is the item again:
As waves of boring information rolled from Professor Clark's mouth.
Kris grabbed his mental surfboard and spent the rest of the hour riding
fantasy waves.
You chose to use Punctuation Rule 2 to fix the problem:
Subordinate Clause + , + Main Clause.
Here is the correction:
As waves of boring information rolled from Professor Clark's
mouth,
Kris grabbed his mental surfboard and spent the rest of the hour
riding fantasy waves.
Well done! You deserve those cyber tacos!