What are the arguments that the bank is not liable to Mansi for paying the checks?

Mary Mansi claims that eighteen checks on her account
contain forgeries but were nevertheless paid by her bank,
Sterling National Bank. The checks bore signatures that,
according to Mansi’s handwriting expert, were apparently
“written by another person who attempted to simulate her
signature” and thus were not considered obvious forgeries.
Sterling National Bank acknowledged that it did honor
those eighteen checks, but nine of them were returned
to the plaintiff more than one year prior to this action.
In addition, Mansi had received bank statements and failed
to examine them.
a. What are the arguments that the bank is liable to Mansi
for wrongfully paying the checks?
b. What are the arguments that the bank is not liable to
Mansi for paying the checks?
c. Who should prevail? Why?