Answer:
6.3
Explanation:
To get from 4.5 to 5.4, you need to add 0.9. If you add 0.9 two more times, you get 7.2. Therefore, the middle term should be 6.3. I don't know if you made a typo and forgot the decimal when writing the options cause it says "63", but I believe the answer is 6.3.
We will verify each options
option-A:

we can factor it



so, this is not irrational.........Answer
option-B:

Since, it can not be factored
so, this is irrational.........................Answer
option-C:

we can factor it



so, this is not irrational.........Answer
option-D:

we can factor it



so, this is not irrational.........Answer
Answer:
1/4
Step-by-step explanation:
-1/8 + 3/8 = 2/8 = 1/4