The income statement of B company for the year ended March 31, 1992 are as follows:

(in millions of pesos)	1992	1991
Sales	320.5	305.4
Cost of sales	274.1	253.9
Gross profit	46.4	51.5
Distribution costs	11.6	10.4

Administrative expenses	22.6	23.5
Other operating income	4.5	6.4
Earnings before interest and taxes	16.7	24.0
Interest charges	1.9	4.3
Earnings before taxes	14.8	19.7

Which one of the following conclusions is correct?

a. The company sold more goods by volume in 1992 than in 1991.

b. The gross margin, as a percentage of sales, was higher in 1992 than in 1991.

c. The increase in distribution costs in 1992 over and above the 1991 amount is due to the higher sales turnover.

d. The net profit margin, as a percentage of sales, fell in 1992 to about 2/3 of its level in 1991