What technology contributed to the defeat of the german luftwaffe in the battle of britain in 1940?

radar
glide bombs
ballistic missiles
plastic explosives

That would be radar.

This was a key battle between Britain's RAF (Royal Air Force) and the Luftwaffe, if the Germans would've won most likely Britain would've been German; and many different outcomes could've happened in the past.

But, since radar was invented, and the British employed it in their tactics; that along with the communication between them helped repel the attack in the Battle of Britain.