Table:
text: PRR locomotive classification
EMD
EMD
PRR_Class Builder_s_Model Build_date Total_produced Wheel_arrangement Service Power_output
ES6 SW 1937 12 B-B Switcher hp (kW)
ES6 SW1 1942–1950 85 B-B Switcher hp (kW)
ES10 NW2 1941–1948 32 B-B Switcher hp (kW)
ES12 SW7-SW9 1950–1953 84 B-B Switcher hp (kW)
ES12 SW1200 1957 35 B-B Switcher hp (kW)
EF15 F3A,F7A 1947–1952 203 B-B Freight hp (kW)
EF15 F3B,F7B 1947–1952 107 B-B Freight hp (kW)
EPF15 FP7A 1952 40 B-B Pass hp (kW)
EPF15 FP7B 1952 14 B-B Pass hp (kW)
EP20 E7A 1945–1949 46 A1A-A1A Pass hp (kW)
EP20 E7B 1945–1949 14 A1A-A1A Pass hp (kW)
EP22 E8A 1950–1952 74 A1A-A1A Pass hp (kW)

Question: Which PRR class has an axle arrangement of a1a-a1a under the PRR locomotive classification EMDs?