Which One of the Following Statements Is True About the Indifference

Multiple Choice

Which one of the following statements is true about the indifference curves for two goods that are perfect substitutes?

A) The indifference curves are negatively-sloped straight lines.
B) The indifference curves are L-shaped.
C) The marginal rate of substitution is zero.
D) The indifference curves are positively-sloped straight lines.
E) The marginal rate of substitution is infinity.