The dimension of the above figure is 9ft×3ft×6ft The home work wants you to recognize where the length, width , and height of the prism. the length runs along the base, the width is the smallest side on this figure, and the height always runs up and down. All the answers below should be circled:
3ft×6ft×3ft
9ft×6ft×1ft
9ft×3ft×3ft does not apply because 6 factored by a third is 2 not 3.