Consider the indifference curve graph below. The slope between points A and C is $\_\_\_\_\_\_\_\_\_\_,$ and this slope is called the $\_\_\_\_\_\_\_\_\_\_.$a$.)1\mathrm{.}8$; marginal rate of substitution $($MRS$)$b$.)1\mathrm{.}2$; marginal rate of transformation $($MRT$)$c$.)1\mathrm{.}2$; marginal rate of substitution $($MRS$)$d$.)1\mathrm{.}8$; marginal rate of transformation $($MRT$)$