Answer:
(c) Exponential
Explanation:
The independent variable in the equation is in the exponent, so this is an exponential equation.
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Additional comment
Linear and quadratic equations are specific cases of polynomial equations, which involve sums of powers of the variables. The highest power involved is the degree of the equation: 1 for linear, 2 for quadratic.
f(x) = x +2 . . . . has x to degree 1, so is a linear equation
f(x) = 3x^2 -5 . . . . has x to degree 2, so is a quadratic equation
f(x) = √(x -6) . . . . is "none of these"
(This is another vocabulary question. Linear, quadratic, exponential, degree, term, polynomial, ... are all words with specific definitions related to algebraic functions.)