The formula \( y = -16t^2 + 40 \) models the height \( y \) of an egg protection contraption at time \( t \) seconds after being dropped.
To interpret this formula in terms of the height of the school’s roof, we look at the initial height at \( t = 0 \).
Substituting \( t = 0 \) into the equation:
\[ y = -16(0)^2 + 40 = 40 \]
This means the height of the school's roof is 40 feet.
Thus, the correct interpretation of the height of the school's roof is:
40 feet.