SAT Question c3d78831: Ratios Rates Proportional Relationships And Units answer and explanation with Desmos solution

Choice B is correct. It's given that at a particular track meet, the ratio of coaches to athletes is $1$ to $26$. If one number in a ratio is multiplied by a value, the other number must be multiplied by the same value in order to maintain the same ratio. If there are $x$ coaches at the track meet, multiplying both numbers in the ratio by $x$ yields $1\left(x\right)$ to $26\left(x\right)$, or $x$ to $26x$. Therefore, the expression $26x$ represents the number of athletes at the track meet.