Hello!
The answer is actually C because irrational numbers cannot be written as a simple fraction.
The other options are also incorrect because of the fact 34/5 is a fraction, not a decimal.
Notice the question says "because it is a _____"
That is where you need to be careful !
It is a fraction, not a decimal, it is also rational, not irrational.
Hopes this helps whoever is reading this ! (✿◠‿◠)
