Use the Following Table to Assist in Answering the Question

Use the following table to assist in answering the question below.
Nuclide
Half-Life
Uranium-238
4) 51 × 10⁹ years
Uranium-234
2) 48 × 10⁵ years
Thorium-230
8) 0 × 10⁴ years
Radium-226
1) 62 × 10³ years
Lead-210
20) 4 years
The rate constant for the decay of unstable nuclide X by alpha-particle emission is 1.17 × 10^-6 / day.What is the identity of X?

A) radium-226
B) thorium-230
C) uranium-238
D) uranium-234
E) lead-210