Why Would a Company Issuing Credit Cards Use a Code

Why would a company issuing credit cards use a code that is much larger than the minimum length?

A) to allow for expansion, since the customer growth may increase exponentially
B) because the numbers are assigned sequentially and the codes should not use all possible numbers
C) so that a person would not be able to guess a credit card number and illegally use it to purchase goods
D) because the codes use the alphabetic derivation format
E) since the codes are used to do inquiries on the data within them