Fact Pattern 33-1 to Buy a House, Mary Obtains a Thirty-Year

Fact Pattern 33-1 To buy a house, Mary obtains a thirty-year mortgage with an interest rate that is fixed for three years and then adjusts annually.
Refer to Fact Pattern 33-1. Mary's mortgage can be described best as

A) a standard mortgage with a fixed-rate of interest.
B) a 30/3 ARM.
C) a 3/1 ARM.
D) none of the choices.