You chose to name the field PrimaryKey so it's clear to other database users that the field is the primary key. However, as you look through other tables, you notice their primary key field names indicate the column's content. You decide you will revisit that later. You've added fields for a client's name, address, city, state, and ZIP code. Now you're ready to add a field for the client's phone number. What data type is the best fit for this field