If 2^{10}10^3 and 5^{20}10^x, then what is the value of integer x?

[GMAT math practice question]

If \(2^{10}10^3\) and \(5^{20}10^x\), then what is the value of integer \(x\)?

A. \(10\)

B. \(12\)

C. \(14\)

D. \(16\)

E. \(18\)