Let M={5,6,7,8} and N={3,4,9,10}. Which one of following functions is neir one-one nor onto?

The function f={(5,3),(5,4),(6,4),(8,9)} is neither one -one nor onto.
The function is not one ? one 8 does not have an image in the codomain N and we know that a function can only be one ? one if every element in the set M has an image in the codomain N.
A function can be onto only if each element in the co-domain has a pre-image in the domain X. In the function f={(5,3),(5,4),(6,4),(8,9)}, 10 in the co-domain N does not have a pre- image in the domain X.
f={(5,3),(6,4),(7,9),(8,10)} is both one-one and onto.
f={(5,4),(5,9),(6,3),(7,10),(8,10)} and f={(6,4),(7,3),(7,9),(8,10)} are many ? one onto.