The gortan-dodd bill requires that a bank disclose to their customers how long they will delay access to funds from deposited checks.

a ) that a bank disclose to their customers how long they will delay access to funds from deposited checks
b) a bank disclose to their customers how long they will delay access to funds from a deposited check
c) that a bank disclose to its customers how long it will delay access to funds from deposited checks

d)a bank that it should disclose to its customers how long it will delay access to funds from a deposited check

e) that banks disclose to customers how long access to funds from their deposited check is to be delayed
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I checked the sub verb agreement and bank discloses OR banks disclose
hence chosed option E
but the OA is C with explaination that its and it agrees with 'a bank'

Now I agree with OA ass option C but how do wee explain this verb - sub agreement ..
Does GMAT hass preference on which errors it rats higher than others

thanks,