7. Function \( f \) is defined by \( f(x)=3^{x} \) What is the \( y \)-intercept of the function? \( \begin{array}{ll}\text { a) } 1 & \text { b) } 0 \\ \text { c) } 6 & \text { d) } 5\end{array} \)

To find the \( y \)-intercept of the function \( f(x) = 3^x \), we evaluate it at \( x = 0 \). By substituting 0 into the function, we get \( f(0) = 3^0 = 1 \). Therefore, the \( y \)-intercept is \( 1 \). So, the correct answer is \( \text{a) } 1 \).