Take a look at the item again:
Because of all his responsibilities at work and
school, (A) Michael had
no time to devote to the yard, (B)
so weeds, vines, and insects thrived in this
jungle. (C)
That neighbors looked on with disapproval.
You wanted to do this:
Because of all his responsibilities at work and
school. Michael had no time to devote to the yard, so weeds, vines,
and insects thrived in this jungle. That neighbors looked on with disapproval.
Adding a period after school will make a fragment. Because of all his responsibilities at work and school is a string of prepositional phrases without the necessary main clause that a complete sentence requires.
You might want to review the rules.
Go back to the sentence to try again.