Here are the main points for an informative speech about the steps of making a cloisonné object.
The first step is shaping the metal into the form of the finished object.
The second step is creating a design by soldering fine wire to the surface of the object.
The third step is filling the design with colored enamel.
The fourth step is polishing the object.
The final step is gilding the object with fluid gold.
 These main points are arranged in __________ order.
A、topical
B、chronological
C、spatial
D、causal