Final answer:
The unacceptable name for an Excel table is option b.(Customers) because it contains parentheses which are not permitted in table names according to Excel naming rules.
Step-by-step explanation:
In Microsoft Excel, table names have specific rules that must be followed. When naming an Excel table, the name must start with a letter or an underscore, cannot include spaces, and must not be the same as a cell reference (like A1 or R1C1). Furthermore, special characters such as brackets, are not allowed in table names. Looking at the provided options, the unacceptable name for an Excel table is b.(Customers) because it contains parentheses which are not allowed in table names.