a: mode
b: mean
c: range
d: median

Answer: Mode: 13, Mean: 10.57, Range: 11, Median: 11
Step-by-step explanation:
How to get mode: Find the number that is the most common in the data set.
How to get mean: Add all of the numbers and then divide the sum by the amount of data that is provided.
How to get range: Subtract the highest number by the lowest number.
How to get median: List all of the numbers low to high and then find the value that is exactly in the middle.