After Becca's half-marathon, her pedometer showed 23, 580 steps, while Alex recorded

2.42 x 104 steps after the same race. What is the combined amount of their steps?

A
4.778 x 103 ; 4,778

B
2.3822 x 104 ; 23,822

C
4.778 x 104 ; 47, 780

D
4.808 x 104 ; 48,080