Answer:
C. Quadrant I
Step-by-step explanation:
For a fact, that with radioactive substance it will decay and never stop halving itself. So the line of amount of radioactive substance always halves in a specific time. This type of graph are done in a positive unit grids, never on a negative because that would mean, the radioactive substance rather decaying, its absorbing. So the answer will be Quadrant I.
Visual likewise graph given below.
