Answer) Graphical representation of consumer 's preferences is given by indifference curve,indifference curve plots the quantities of 2 goods and represent the curve where consumer get maximum satisfaction given the constraints,all points on this curve represents preferences of customer where they are equally satisfied,any indifference curve below another indifference curve represents lower preference while a higher indifference curve represents higher preference,thus given all the constraints,indifference curve is able to plot consumer preferences.

So correct answer is a) Indifference curves