The probability P(A) that an event A occurs is the number of the favorable outcomes (n) divided by the number of total outcomes (N):

In this exercise,
The number of favorable outcomes is the number of yellow cars.
So, n(A) = 11
The number of total outcomes is the number total of cars. So, is the sum of yellow, black, silver, and white cars.
N = 11 + 9 + 14 + 6
N = 40
Substituting it in the formula:

P(A) = 27.5%.
Answer: Alternative D. 27.5%.