Mode: the number that occurs the most in a set of numbers.
Least to greatest - 11,12,12,14,16,18,19,19,20
The answer would be "B" 12 and 19.
The answer would be "B" because both he numbers 12 and 19 appear more than once in this set of numbers. No other number appears more than once so that means that the mode is 12 and 19.