Which of the following represents the set of possible rational roots for the polynomial shown below?

x^3+5x^2-8x-20=0

a.{1/2, 1,2, 5/2, 4, 5, 10, 20}
b. {+/-1, +/-2, +/-4, +/-5, +/-10}
c. {+/-1/2, +/-1, +/-2, +/-5/2, +/-4, +/-5, +/-10, +/-20}
d. {+/-2/5, +/-1/2, +/-1, +/-2, +/-2/5, +/-1/5, +/-1/10}

You need to work out the variables of 20 (the last number) first: 
1, 2, 4, 5, 10, 20 
Lets call these folks "p" 
At that point you need to work out the components of the main coefficient (the number before the most astounding force of x): 
1 
Lets call this person "q" 
At that point you need to make all the conceivable divisions you can with: 
±p/q 
Since q is only 1, we are fortunate, so the conceivable normal roots are: 
±1/1,±2/1,±4/1,±5/1.±10/1,±20/1