The table shows the decay rate for a certain radioactive material over time. In this context, what does the y-intercept represent?

At 100 hours, there are 0 grams of the substance remaining.
At 100 hours, there are 100 grams of the substance remaining.
At 0 hours, there are 100 grams of the substance remaining.
At 0 hours, there is 1 gram of the substance remaining.

It's C