Which one is a synthetic material? A:have only negative effects on the environment
B:are obtained directly from nature
C:have undergone chemical reactions
D:have no similarity to materials in nature

(10 points) 1. cone 2. rectangle 3. triangle 4. circle 5. cylinder a. perpendicular cross section of a pyramid b. perpendicular cross section of a cylinder c. parallel cross section of a sphere d. shape created when a rectangle is rotated about the y-axis e. shape created when a right triangle is rotated about the y-axis