Which table represents a quadratic function?

The first table.

Step-by-step explanation:

In a quadratic function, the second differences are the same.

In the first table, the first differences are:

3-6 = -3;

2-3 = -1;

3-2 = 1;

6-3 = 3

The second differences are then:

-1--3 = 2;

1--1 = 2;

3-1 = 2

The second differences are the same, so this is a quadratic function.