Which of the following BEST explains how a radium isotope with a half-life of about 1,600 years can be found in the crust of the Earth that was formed millions of years ago:

W) its decay is slowed by the pressure of the Earth

X) the radium is replenished by decay of longer lived radioactive elements

Y) the radium was replenished by meteors and asteroids over the millennia

Z) the radium is recycled from the Earth's core where magnetic fields slow the decay
X) THE RADIUM IS REPLENISHED BY DECAY OF LONGEY LIVED RADIOACTIVE ELEMENTS