Answer:
A and D are true.
Step-by-step explanation:
A function is a relationship that maps elements from one set (the domain, set of the inputs) into elements from another set (the range, set of the outputs), such that each element from the domain can be mapped into only one element from the range.
So, if the inputs are represented in the horizontal axis, and the outputs are represented in the vertical axis, when we draw a vertical line in any given point, this line can not intersect the graph more than once (because that would mean that a given input has two different outputs). This is known as the vertical line test. Note that two different values from the domain can be mapped into the same value in the range.
Also, we define a function as one-to-one if each output is mapped from only one input.
(so here we can not have two different inputs mapped into the same output).
Here we can do a similar test to the one above, this time we should use the horizontal line test to verify if the function is one-to-one or not.
So, here the correct options are:
A and D.
Option B is false.
And for option C, a sequence is a function where the variable is a set of natural numbers, so option C is also false.
