Lets review the options one by one:
X A.) The question says the y must be less than 100, not less than or equal to.
X B.) The y becomes 0, but 0 is neutral, not a positive number.
X C.) The height must be positive at all times, according to the range given.
√ D.) The given graph contains a max with a positive number under 100.
Therefore, the correct answer choice would be Option D (4).
Hope this helps! :)