Which, if any, of the following would not generate a sphere? A. Rotating a circle 180° about its diameter
B. Rotating a semicircle 360° about its diameter
C. Rotating a circle 360° about any point on the circle
D. All of the above would generate a sphere

Suppose you are choosing a 6-digit personal access code. this code is made up of 4 digits chosen from 1 to 9, followed by 2 letters chosen from a to z. any of these digits or letters can be repeated. find the total number of personal access codes that can be formed. 492,804 341,172 39,917,124 4,435,236