由sin(A-B)+2cosAsinB=-2sin2C,
∵sinAcosB-cosAsinB+2cosAsinB=sin(A+B)=sinC,
∴sinC=-2sin2C=-4sinCcosC,
∵sinC≠0,∴cosC=-
,∴sinC=1 4
=
1?cos2C
.
15
4
∵16a2+16b2-13c2=0.∴?
=cosC=1 4
=
a2+b2?c2
2ab
,化为6(a2+b2)=13ab.
a2+b2?
(a2+b2)16 13 2ab
∵△ABC的面积为
,∴3
15
4
absinC=1 2
ab×1 2
=
15
4
,化为ab=6.3
15
4
∴(a+b)2=a2+b2+2ab=
ab+2ab=13 6
×6=25.25 6
∴a+b=5.
故选:A.