2)let the roots be cisP,cisQ,cisR.

b=cis(P+Q)+cis(Q+R)+cis(R+P)

on simplification IbIsquared=3+2cos(P-Q)+2cos(Q-R)+2cos(R-P)

IbImax=3,when P=Q=R

also -a=cisP+cisQ+cisR

on simplification IaIsquared=3+2cos(P-Q)+2cos(Q-R)+2cos(R-P)=IbIsquared

IaImax=3

therefore option 1,2,3 are correct.