Which of the following is the correct factor tree of $30$?

The given number is $30$ and we have to identify the correct factor tree for the given number.

While making the factor tree for any number, we begin with the smallest prime factor.

The smallest prime factor of $30$ is $2$.

So we will begin with $2$.

So, the correct factor tree is

This factor tree is not correct as $3$ is not the smallest prime factor of $30$.

This factor tree is not correct as $15$ is not a prime number.

This factor tree is not correct as $10$ is not a prime number.

Hence, option A is correct.