Final answer:
To determine the number of days Margo has owned the plant, use the equation d = (65 - 5) / 2.5.
Step-by-step explanation:
To determine the number of days Margo has owned the plant, we can use the equation d = (65 - 5) / 2.5 as the correct option is a. This equation calculates the number of days by taking the difference between the current height of the tree (65 cm) and the initial height when Margo bought it (5 cm), and then dividing that by the daily growth rate (2.5 cm per day).