Manero Company included the following information in its annual report:

	2019				2018				2017
Sales	$	178,400			$	162,500			$	155,500
Cost of goods sold		115,000				102,500				100,000
Operating expenses		50,000				50,000				45,000
Operating income		13,400				10,000				10,500

In comparison to year 2017, the effect of sales growth on operating income of 2018 was (ignore taxes):

Group of answer choices

a $473.

b $431.

c $7,000

d $6,667.