A) The window was shivering with frost.
b)The aggressive exam challenged the intellect of the student.
c) The trail beckoned the running dog forward.
d) The jelly beans looked like they spontaneously scampered around the table.
The appositive is usually a group of words related to a noun, usually a subject, and describes it in more detail.
The appositive here is a river that flows through Egypt.
Another way of easily spotting an appositive is by looking for commas - if it is separated from the rest of the sentence by commas, it is likely to be an appositive.
The correct answer would be B. Present. Hope this helps!