How many parent isotopes based on half lives

Okay, so, after one half-life has passed, there will still be 50 units of the parent isotope, and 50 units of the daughter product will have been produced. And then after another half-life, 25 units of the parent isotope will still be there, and 75 units of the daughter product will have been produced.

hope i helped and brainliest is always appreciated :)

the answer is c) an oak tree