Considering that there is no real question content here, we can't be for sure, so I am just going to say 100% probability since it seems like that is the only card he can pick from ; ~ ;
Think the answer is C or A i think its C though
we are given

Since, we have to solve for t
so, we will isolate t on anyone side
divide both sides by 3

now, we can take ln both sides

we can simplify it

divide both sides by 4ln(r)
..............Answer