The correct answer is: A. a minimum.
The function $f(t) = \frac{\sin t}{t}$ is continuous for all real numbers. It has a horizontal asymptote at $y = 0$. The function has a minimum at $t = 0$, where $f(0) = 0$.
A minimum is a point on a graph where the function value is lower than the values of the function on either side of the point. In other words, a minimum is a point where the function is decreasing and then starts increasing.
A discontinuity is a point on a graph where the function is not continuous. There are two types of discontinuities: removable discontinuities and non-removable discontinuities. A removable discontinuity is a point where the function can be made continuous by changing the value of the function at that point. A non-removable discontinuity is a point where the function cannot be made continuous by changing the value of the function at that point.
A point of inflection is a point on a graph where the concavity of the graph changes. In other words, a point of inflection is a point where the graph goes from concave up to concave down or vice versa.