以下程序的输出的 CSV 文件里，存储的内容是：( )
file = open('text.csv','w')
list =[ [90,87,93],[87,90,89],[78,98,97]]
b = []
for i in list:
for j in i:
b.append(str(j))
file.write(','.join(b))
file.close()
[90,87,93,87,90,89,78,98,97]
90,87,93 87,90,89 78,98,97
[[90,87,93], [87,90,89], [78,98,97]]
90,87,93,87,90,89,78,98,97