Is this right , tell me the correct answer ?

Given that 'number of smartphones' means 'number of smartphones sold', i and ii are right. A function is something where each x value corresponds with exactly one y value, and it seems to be so because none of the values shown overlap.

Does the problem say y=x+4?

First locate the turning point (vertex) of the graph. which is at the coordinates x=5 and y=9 or (5; 9).to determine whether it's a maximum or mininum value, you have to discern whether the vertex's y-value is the highest value or lowest value the graph can reach. since the vertex's y-value, 9 is the highest value the graph can reach, it will be a maximum.another basic way to determine whether the vertex's value is max or min is to see if the graph is smiling or sad. if it's smiling, the turning point/vertex would be a minimum, while a sad parabola would have a maximum y-value at the vertex.