Let $A = \{1, 2, 3\}$, $B = \{4, 5, 6, 7\}$ and let $f = \{(1, 4), (2, 5), (3, 6)\}$ be a function from $A$ to $B$. Based on the given information, $f$ is best defined as

injective function

The correct answer is Option (2) → injective function ##

Reasoning:
Given
A = {1, 2, 3}, B = {4, 5, 6, 7}
f = {(1,4), (2,5), (3,6)}

Different elements of A map to different elements of B, so the function is one–one (injective)
Element 7 ∈ B has no pre-image, so it is not onto.