3. find the mass and the center of mass of the lamina occupying the region r, where r is the region bounded by the graphs of y = sin3x, y=0, x=0, and x = π/3, and having the mass density ρ(x, y) = 4y.

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.

A

Ithink it’s d as the answer.