Uranium (U-231,92) has a half-life of about 4 days and decays into thorium (Th-227,90), which is relatively more stable. A quantity of 8 grams of uranium is placed in a container, and the contents are checked after 12 days. Which of the following correctly predicts the ratio of uranium to thorium atoms in the container and the nuclear process that took place?
A.) 1:7, alpha particle emission
B.) 1:2, alpha particle emission
C.) 1:2, positron emission
D.) 1:7, nuclear fission and gamma emission