The answer is A just trust me
6. 24- factors:1&24,2&12,3&8, 4&6. 18 factors: 1&18, 2&9, 3&6. The highest number that can multiply into them is 6 so it is the GCF
It opens upward and the vertex is (2,-6) here are some plotted points: (0,6),(1,-3),(2,-6),(3,-3),(4,6). Hope that helps. I hate graphing but if you do it enough times you'll get the hang of it!