Choose the correct order in which the sentences make a meaningful passage.
1. the noise caused by the lightning is called thunder.
2. finally it discharges, causing a huge spark, or lightning, to fly out.
3. thunder and lightning occur when air currents form a storm cloud.
4. inside the cloud, a massive electrical charge builds.
(a) 1, 3, 2, 4
(b) 3, 4, 2, 1
(c) 3, 4, 1, 2
(d) 1, 3, 4, 2