Psychologist Gloriayn Rovee-Collier Placed Babies on Their Backs Under a Colorful

Psychologist Gloriayn Rovee-Collier placed babies on their backs under a colorful crib mobile and tied a ribbon around the baby's ankle, connecting it to the mobile.Whenever the babies spontaneously kicked their legs, the mobile jingled and rattled.Within minutes, infants as young as what age learned to control their movements and kick faster to move the mobile more?

A) three months
B) six months
C) nine months
D) 12 months