It is rational because any number that can be represented in a fraction is rational. 4/33 is a fraction, so it is rational.
The graph you chose has a y intercept of 5. In other words, the point (0,5) is on that graph. However, if we plugged x = 0 into the function f(x), we get
f(x) = 3*5^x
f(0) = 3*5^0
f(0) = 3*1
f(0) = 3
So the point (0,3) is actually on the graph. The graph is increasing. So the answer is the upper left corner (instead of the upper right corner)
For an exponential function the y-intercept is the "initial value" (not the common ratio).

will always be 2. if that's what you need
note that

because anything to the power of zero equals 0 (mathematically it's deciding something by itself)