问题如下：
XYZ company's sales were $600,000 in 2017, and its average accounts receivables is $50,000. XYZ's receivables collection period in 2017 is closest to:
选项：
A. 12 days.
B. 30 days.
C. 41 days.
解释：
receivables turnover = (revenue / average account receivable) = 600 / 50 = 12
receivables collection period = 365 / 12 = 30.4167 days
请问这题怎么理解？不懂啊，能解释一下吗？