Write the line as $y = 3x + b$, then plug in $x=2$ and $y=5$ because the point $(2,5)$ is on the line.

After substituting, isolate $b$ by performing the same operation on both sides of the equation.

Type the equation $y - 5 = 3(x - 2)$ into Desmos. This represents a line with slope $3$ passing through $(2,5)$.

Look at where the line crosses the $y$-axis (where $x=0$). Click that intersection point; the $y$-coordinate of this point is the $y$-intercept you want.

A line with slope $m$ and $y$-intercept $b$ can be written as

Here, the slope is $3$, so the equation becomes

The line passes through $(2,5)$, so $x=2$ and $y=5$ must satisfy the equation.

Substitute $x=2$ and $y=5$ into $y = 3x + b$:

Now solve for $b$:

So the $y$-intercept of the line is $-1$, which corresponds to choice B.