In the early stages of a project, the allowable cumulative cost variances are +/- 19%. Which elements require an explanation? (Note: Figures are in millions of dollars)

Options given are

A)P and R   B) P, Q and R   C) Q, R and S  D)P,Q and S

Answer given is          Pand R

I have calculated as follows:

CV = EV-AC

For item P, cost variance = (6-8)*100/8 = -25%

For item Q, cost variance is (8-9)*100/9 = -11.11%

For item R, cost variance is (10-12)*100/12 = -16.67%

For item S, cost variance is (11-9)*100/9 = +22.2%

So, items P and S are to be looked into, for which cost variance is not within limits. But the answer is given as Pand R

Can someone explain, as to where am I going wrong?