Answer
(b) is the right answer.
Work Step by Step
We know that the answer is (b) because $\ln t=c$ leads to $t=constant$. Thus, for any value for $y$, $t$ will be a constant.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.