Wich sum is rational

C

Step-by-step explanation: “Rational” means that the number can be written as a non-terminating, non-repeating fraction. With that in mind, we can look at the answer choices. You might already know that pi is an irrational number; if you didn’t, it’s because it’s goes on infinitely without repeating. You can then eliminate A and D since they have pi in them. That leaves B and C. B can also be eliminated since the square root of 73 is non-terminating & non-repeating; that leaves only C. To check, C can be written as 13/2, which fulfills the requirements needed for a number to be rational.