Identify the error in the sentence, if any:
Neither the Bank manager nor the other/(1) staff members was able/(2) to calm the distressed client./(3) No Error/(4)

When using the correlative conjunction "neither...nor", the verb should agree with the noun phrase that is closer to it. In this sentence, the noun phrase closer to the verb "was" is "the other staff members", which is plural. Therefore, the verb should also be plural.

The correct sentence should be:

"Neither the Bank manager nor the other staff members were able to calm the distressed client."

Therefore, the correct option is was able.