Which is a description of the vertical shift of the function f(t)=3sec(t-pi/4)-2

The vertical shift of the given function is -2 or down 2. (Option D)
Here's why:
The function is given in a form of:
[tex]f(t)=a\sec (bx-c)+d[/tex]where d is the vertical shift. Since -2 is the value of d in the given function, then, -2 is the vertical shift.