Is r(t)\displaystyle {r}{\left({t}\right)} represented in the list of ordered pairs below a function?

r(t)={(3,5),(4,4),(5,2),(6,3),(7,2),(8,4)}\displaystyle {r}{\left({t}\right)}={\left\lbrace{\left({3},{5}\right)},{\left({4},{4}\right)},{\left({5},-{2}\right)},{\left({6},{3}\right)},{\left({7},-{2}\right)},{\left({8},-{4}\right)}\right\rbrace}