Which of the following fractions is the smallest?

My approach:

List the numbers up from 3/10 - 6/19 - 3/8 - 11/30 - 12 / 31

Look for the pattern - obviously they want something from us that involves 1/3 because all numbers are suspiciously close to 1/3
So let's check

3/10 = 0,30 -> another way to check is to perform 3*3 which is 9 and means it is slightly smaller then 1/3
6/19 = x -> 6*3 = 18 so this one is slightly smaller than 1/3 as well

Now with the following three you immediately are going to recognize that all of the numbers *3 lead to something greater then the whole fraction, which means all of those numbers are greater then 1/3 and therefore can be eliminated.

With the last two numbers you probably have several options to check which one is larger / smaller, I just went with simple divsion.
Because I already knew that 10/30 is 0.30 so I basically wrote 6/19 and immediately saw that it's something like 0.31xxxx

So therefore I choose a)

Correct me if wrong