Idon’t understand this and need the answer.

The answer should be C

The reason for this is because:

There are 2 "I" on the right side of the equation but only 1 on the left. This means you need to add a 2 on the "KI" to get two "I".

But now there are 2 "K" on the left side and only 1 on the right, meaning you need to add a 2 to the "KCL". This makes it balanced