[单选题]
08.19: Kepler’s Second Law about “sweeping out equ lz4) c iwv2:jk5cis,ral kjg pm9)w *t7qe.wq8kareas in equal time” can be derived most direc*tp 78.q9wew m kjgq)ktly from which conservation law?
A. energy
B. angular momentum
C. linear momentum
D. mechanical energy
E. mass
