Here is the original item:
Darryl has the messiest book bag
(A) of anyone
Rachel knows;
(B) he essentially
has a compost pile rotting in the main
compartment. (C)
For instance,
pistachio shells, pencil shavings, and a brown banana.
You wanted to do this:
Darryl has the messiest book bag of anyone Rachel
knows, he
essentially has a compost pile rotting in the main compartment. For instance,
pistachio shells, pencil shavings, and a brown banana.
Changing the semicolon to a comma is a mistake. You have two main clauses at this juncture, and a comma is too wimpy a punctuation mark to connect them. There is a fragment to fix. Look more closely!
You might want to review the rules.