After mastering snappy soul, this classic Motown girl group expanded their range. “Honey Chile”, from 1967, gives its subject an inventively rhyming tongue-lashing that foreshadows hip-hop, while the band react to the Vietnam War with 1970's powerful protest song “I Should Be Proud”. And on 1972's emotional ballad “In and Out of My Life”, they dig even deeper—without sacrificing those satisfying grooves.