Consider a finite graph $G$: $G$ is a tree if it satisfies any of the following equivalent conditions:
(1) $G$ is connected and no cycle can be a subgraph of $G$.
(2) $G$ is connected and no cycle can be an induced subgraph of $G$.
If $G$ is infinite (countably), clearly (1) implies (2) but does (2) imply (1)?
Hint (same proof as for the finite case)