What is the best next step in the construction of a line that passes through point c and is parallel to ab? (assume that the arc drawn with the compass placed at point a was the result of the last step performed.)

a. using the same compass setting, place the point of the compass at b and draw an arc that intersects ab.

b. change the compass setting, and draw an arc with point of the compass at point a that passes through point b.

c. using the same compass setting, place the point of the compass at c and draw an arc that intersects ab.

d. change the compass setting, and draw an arc with point of the compass at point a that passes through point c.

For every corresponding pair of cross sections, the area of the cross section of a sphere with radius r is equal to the area of the cross section of a cylinder with radius and height 2r minus the volume of two cones, each with a radius and height of r. a cross section of the sphere is and a cross section of the cylinder minus the cones, taken parallel to the base of cylinder, is the volume of the cylinder with radius r and height 2r is and the volume of each cone with radius r and height r is 1/3 pie r^3. so the volume of the cylinder minus the two cones is therefore, the volume of the cylinder is 4/3pie r^3 by cavalieri's principle. (fill in options are: r/2- r- 2r- an annulus- a circle -1/3pier^3- 2/3pier^3- 4/3pier^3- 5/3pier^3- 2pier^3- 4pier^3)