SAT Question 4c5ea142: Ratios Rates Proportional Relationships And Units answer and explanation with Desmos solution

Choice D is correct. It’s given that on average, a certain plant grows $87$ millimeters every $m$ months. This average rate can be written as $\frac{87}{m}$ millimeters per month. Since there are $12$ months in $1$ year, it follows that there are $12k$ months in $k$ years. Therefore, the number of millimeters, on average, the plant grows every $k$ years can be calculated by multiplying the rate $\frac{87}{m}$ millimeters per month by $12k$ months, which yields $\left(\frac{87}{m}\right)(12k)$, or $\frac{1,044k}{m}$.