What does it mean by saying 'Tropical waves, the embryos of many tropical cyclones' (Line 1, Para.7)? 查看材料
A.
Tropical waves are the early stage of many tropical cyclones.
B.
Tropical waves are the final stage of many tropical cyclones.
C.
Tropical waves are core parts of many tropical cyclones.
D.
Tropical waves are the only part of many tropical cyclones.