The correct answer is: A. The marginal rate of substitution is high and the indifference curve is steep.
The marginal rate of substitution (MRS) is the amount of one good that a consumer is willing to give up to obtain one more unit of another good, while remaining at the same level of satisfaction. The MRS is measured at a point on an indifference curve.
An indifference curve is a curve that shows all the combinations of two goods that a consumer is indifferent between. In other words, the consumer is equally satisfied with any combination of goods that lies on the indifference curve.
The MRS is high when a consumer is willing to give up a lot of one good to obtain a small amount of another good. This means that the consumer values the two goods differently. The MRS is low when a consumer is not willing to give up much of one good to obtain a small amount of another good. This means that the consumer values the two goods equally.
The indifference curve is steep when the MRS is high. This means that the consumer is willing to give up a lot of one good to obtain a small amount of another good. The indifference curve is shallow when the MRS is low. This means that the consumer is not willing to give up much of one good to obtain a small amount of another good.
In the question, the consumer requires a small amount of the good measured along the Y-axis to make up one unit less of the good measured on the X-axis. This means that the consumer is willing to give up a lot of the good measured along the Y-axis to obtain a small amount of the good measured on the X-axis. Therefore, the MRS is high and the indifference curve is steep.