Which relation is a function?

{(2, 3), (1, 5), (2, 7)}
{(-1, 5), (-2, 6), (-3, 7)}
{(11, 9), (11, 5), (9, 3)}
{(3, 8), (0, 8), (3, -2)}

the highest percentage for deaths in construction from highest to lowest is as follows: falls, struck by objects, electrocution, and caught-in/between. these four are collectively known as fatal four.

in the case of falls, the type that is responsible for the overall highest death in the category is falls from roofs.