Numere a 2ª coluna, relacionando as perguntas às suas respectivas respostas.

I. What is coal ?

II. How is oil formed?

III. Why is coal widely used in generation of electricity?

IV. How is natural gas formed?

( ) In the same way as oil.

( ) A solid fuel formed by the decay of land vegetation.

( ) From the remains of marine micro-organisms deposited on the sea floor.

( ) It is a highly concentrated energy source.

A seqüência correta obtida, de cima para baixo, é: