One-to-one functions

Please complete the attached document? It contains the following questions: Which of these graphs represent a one-to-one function?

Based on data about the growth of a variety of ornamental cherry trees, the following logarithmic
model about these trees was determined:
h(t) = 6.018 ln(t) + 6.079, where t = age of tree in years and h (t) = height of tree, in feet.
(Note that “ln” refers to the natural log function) (explanation optional)
Using the model,
(a) At age 3 years, how tall is this type of ornamental cherry tree, to the nearest tenth of a foot?
(b) At age 10 years, how tall is this type of ornamental cherry tree, to the nearest tenth of a foot?