问题：
[单选题]一些希腊的哲学家认为一切物质都是由四种元素构成,那就是土、火、空气和水。于是很多人就认为如果把这些元素重新组合的话,一种物质就可能变成另一种物质。()
A
Some Greek philosophers held that all matter was made up of the same four elements, which are earth, fire, air and water. So many people thought that if these elements could be rearranged, one substance could be changed into another.
B
Some Greek philosophers held that all matter was made up of the same four elements—earth, fire, air and water; and many people therefore thought that if these elements could be rearranged, one substance could be changed into another.
