Question

The graph below shows three functions:

Graph of function f of x equals 2 to the power of negative x. Graph of function g of x equals 5 to the power of x. Graph of p of x is a line segment connecting points negative 1, negative 3 and 2, 12.

Which function has all real numbers as its domain?

Only f(x)
Both g(x) and p(x)
Both f(x) and g(x)
Only p(x)