Two petri dishes were on the desktop in Dr. McFarlan's lab.

Dish A had cells with a radius of 3.6 × 10-10 cm. Dish B had cells that had a radius of 3.1 × 10-8 cm. What is the sum of the radii of the two types of cells, using scientific notation?
A.
3.136 × 10-12 cm
B.
3.136 × 10-8 cm
C.
313.6 × 10-10 cm
D.
31.36 × 10-11 cm