Here is the formula that will help to solve this task: P1/T1 = P2/T2
Keep in mind that value 20 C is an equivalent to 293 K.
If you have to make new pressure 12.4 atm, the given temperature must be changed intor 284K.
Therefore:
The correct answer is B)At 15.4 atm, T2 would have to be 353 K (which is 120 C)
As you can see, these options are not suitable:
At 16.6 atm, T2 would have to be 381 K
At 18.6 atm, T2 would have to be 426 K