Take a look at the item again:
Citing writer's block as the reason
(A) that she didn't have her
essay, (B)
Yao received no sympathy from Mrs. Santos.
(C) Who will only accept
"breather's block" as a legitimate excuse for late work.
You wanted to do this:
Citing writer's block as the reason, that
she didn't have her essay, Yao received no sympathy from Mrs. Santos. Who
will only accept "breather's block" as a legitimate excuse for late work.
Adding a comma after reason not only is incorrect but also fails to fix the fragment that still exists. You need to reconsider your options.
You might want to review the rules.
Go back to the sentence to try again.