In the set of all past due accounts, let the event A mean the account is between 31 and 60 days past due and the event B mean the account is that of a new customer. The intersection of A and B is

all new customers

all accounts fewer than 31 or more than 60 days past due

all accounts from new customers and all accounts that are from 31 to 60 days past due

all new customers whose accounts are between 31 and 60 days past due