Maths question please answer

Top left, bottom left, & bottom right are functions

Step-by-step explanation:

To be considered a function, you must have no repeating X variable. Column A represents X, Column B represents Y.

The top left and bottom left diagrams show the A numbers going to one single B number, there is no A number with two lines going to a B number.

The bottom right may have two lines going to a B number, but there is no A number with two lines, still making it a complete function.

Now for top right, in the A column, variable d clearly has 2 lines making it not a function.

Hope this makes sense! :)