Final answer:
The question cannot be answered without specific deer population numbers for the years 1923 and 1926. The calculation for percentage decrease requires the initial and final population values to determine the change.
Step-by-step explanation:
The information given does not provide specific numerical data for the deer populations in 1923 and 1926, which is necessary to calculate the percentage decrease in deer population between those two years. As such, you cannot accurately determine the percentage decrease without additional data regarding the populations in 1923 and 1926.
To calculate the percentage decrease, you would need the population numbers for both years. Once you have those numbers, you'd subtract the later year's population from the earlier year's population to find the difference. Divide that difference by the earlier year's population and multiply by 100 to get the percentage decrease.
Without the specific population figures, we can't perform this calculation. Thus, none of the given choices (a. 5%, b. 10%, c. 15%, d. 20%) can be verified as the correct answer to your question. In these cases, it's important to ask for clarification or additional data that would enable accurate computation of the percentage.