[单选题]
The potential difference 13h7n7 vo +gudcimhdy97j p p+between the terminal5hshi:v hw5l5 o8ew.u s of a battery, when current flows to an external circuit, is referred to as the8s :w w5v5hhh5oiue l.
A. battery emf
B. terminal voltage
C. battery power
D. battery rating
