Final answer:
The function that decreases throughout the interval x:2 is the quadratic function. The correct answer is d.
Step-by-step explanation:
Based on the given information, the function that decreases throughout the interval x:2 is the quadratic function. A quadratic function is a polynomial function of degree 2, and it has a graph that is a parabola. The general equation of a quadratic function is y = ax^2 + bx + c, where a, b, and c are constants. In a quadratic function, the coefficient of x^2 determines whether the parabola opens upward (if it is positive) or downward (if it is negative).
Therefore the correct answer is d.