Choice "B" is correct. The average number of days to collect accounts receivable is calculated by dividing 365 days by the accounts receivable turnover. Accounts receivable turnover is net credit sales divided by the average accounts receivable:

Choice "c" is incorrect. The denominator should be net credit sales ($7,200) divided by average receivables $1,000), or 7.2, not 12.
Choice "d" is incorrect. The average receivable balance is $1,000, not $800. The right-hand column shows the increase over Year 1, so the Year 1 receivable balance was $1,200 - $400, or $800. Since the Year 2 receivable balance was given as $1,200, the average receivable balance is $1,000.
Choice "a" is incorrect. Average inventory ($1,000), not ending inventory ($1,200), should be used.