What pseudo code would the developer use to avoid a buffer overflow attack on the billing address field?

A developer for a company is tasked with creating a program that will allow customers to update
their billing and shipping information. The billing address field used is limited to 50 characters.
What pseudo code would the developer use to avoid a buffer overflow attack on the billing address
field?

A.
if (billingAddress = 50) {update field} else exit

B.
if (billingAddress != 50) {update field} else exit

C.
if (billingAddress >= 50) {update field} else exit

D.
if (billingAddress <= 50) {update field} else exit