Final answer:
Option (3) h = -1/100 d² + 75d + 3 is the most realistic quadratic function to model the height of a javelin throw as it describes a parabolic trajectory where the javelin reaches a maximum height before descending.
Step-by-step explanation:
The question asks for a realistic quadratic function to model the height of a javelin above the ground in relation to the horizontal distance it has traveled.
Given that the height starts at a certain point above the ground and then reaches a maximum before coming back down, option (3) h = -1/100 d² + 75d + 3 is the most realistic function.
This is because the negative coefficient in front of the d² term indicates that the height reaches a maximum and then decreases, which is typical for the trajectory of a projectile, like a javelin throw.
The other functions would suggest that the javelin keeps ascending indefinitely or starts below the ground level, which are not physical scenarios.