Immature forms of many animals, like guinea worms, before they morph into adults

The immature forms of animals which they are before metamorphosis are the larva.

Explanation:

The larva in plural form is known as the larvae. The eggs are hatch into the form of larva. These larvae grow in different stages which are marked according to the stages as I or II and so on.

After the larval development, when they are ready to be converted into adults, metamorphosis occurs. This process changes the larva into adults. Here the immature form gets converted into mature adult form.

causes

fossil fuels burn

cities become more industrialized

human population grows worldwide

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.