Calculate the line integral ( ∮_C vecF ⋅ vecr' , ds ) by Stokes's theorem, clockwise as seen by a person standing at the origin, for ( vecF= [-3y, 3x, z] ), ( C ) the circle ( x² + y² = 10 ), ( z = 1 ). NOTE: Enter the exact answer.
a) ( -15π )
b) ( 15π )
c) ( 10π )
d) ( -10π )