Seismic Tomography Has Revealed That Seismic Waves in the Uppermost

Seismic tomography has revealed that seismic waves in the uppermost mantle are relatively

A) fast beneath both mid-ocean ridges and subduction zones.
B) fast beneath mid-ocean ridges and slow beneath subduction zones.
C) slow beneath mid-ocean ridges and fast beneath subduction zones.
D) slow beneath both mid-ocean ridges and subduction zones.