SAT Question 1e1027a7: Two-variable Data Models And Scatterplots answer and explanation with Desmos solution

Choice D is correct. On the line of best fit, $d$ increases from approximately $480$ to $880$ between $t=12$ and $t=24$. The slope of the line of best fit is the difference in $d$-values divided by the difference in $t$-values, which gives $\frac{880-480}{24-12}=\frac{400}{12}$, or approximately $33$. Writing the equation of the line of best fit in slope-intercept form gives $d=33t+b$, where $b$ is the $y$-coordinate of the $y$-intercept. This equation is satisfied by all points on the line, so $d=480$ when $t=12$. Thus, $480=33\times 12+b$, which is equivalent to $480=396+b$. Subtracting $396$ from both sides of this equation gives $b=84$. Therefore, an equation for the line of best fit could be $d=33t+84$.