Which one of the following is an example of a thermosetting polymer?

A thermosetting polymer which is also known as a thermoset or thermosetting plastic is a polymer consisting of cross-linked structure or heavily branched molecules.

$\left(1\right)$ Neoprene is an elastic polymer.
$\left(2\right)$ PVC is a thermoplastic
$\left(3\right)$ Nylon $- 6, 6$ is a fibre
$\left(4\right)$ Bakelite is a thermosetting polymer