Which activates a convection current, starting the flow of a fluid? a. cold temperatures at the north pole b. heated liquids at earth's surface c. iron-rich rocks in the mantle d. temperature differences in the mantle

(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