An Alexa Skill Builder Is Creating a Skill That Requires

An Alexa Skill Builder is creating a skill that requires the user to authenticate by speaking a PIN before an order status can be retrieved. According to best practices, how should the PIN value be collected?

A) Use AMAZON.SearchQuery Use AMAZON.SearchQuery
B) Use AMAZON.FOUR_DIGIT_NUMBER AMAZON.FOUR_DIGIT_NUMBER
C) Use multiple slots of type AMAZON.NUMBER Use multiple slots of type AMAZON.NUMBER
D) Use a custom slot with zero to nine as values.