ANSWER
Options B and D are Not True.
Step-by-step explanation
A. The horizontal line test can be used to determine whether a function is one-to-one.(True)
B. If a relation has each input value paired with at least one value of the output variable, then it is a one-to-many relation. This relation is not a function.
It will fail the vertical line test. (Not True)
C. A sequence is a function whose domain is the set of natural numbers this explains why we cannot draw a smooth curve for its graph. We just use dots.
(True)
D. The vertical line test is only used to determine if a relation is a function.(Not True)