Final answer:
The ratio of blue to white cars in the parking lot is 12:24.
Step-by-step explanation:
The ratio of blue to white cars can be found by dividing the number of blue cars by the number of white cars. In this case, there are 12 blue cars and 36 total cars. So, the ratio is 12:24, which simplifies to 1:2. Therefore, the correct answer is 3) 12:24.