Oliveras Company had net credit sales during the year of $800,000 and cost of goods sold of $500,000. The balance in accounts receivable at the beginning of the year was $100,000, and the end of the year it was $150,000. What were the accounts receivable turnover and the average collection period in days?

a.	7.3 and 64 days.

b.	4.0 and 91.3 days.

c.	6.4 and 57 days.

d.	8.0 and 45.6 days.