Read the following statements and choose the following option: 1. About 5000 million years ago (mya) the first cellular forms of life appeared on earth 2. The mechanism of how non-cellular aggregates of giant macromolecules could evolve into cells with membranous envelop is not known. 3. Single-celled organisms became multi-cellular life forms by the time of 500 mya 4. Jawless fish probably evolved around 350 mya.

Step-by-step solution

Giant ferns (pteridophytes) were present but they all fell to form coal deposits slowly. Some of these land reptiles went back into water to evolve into fish like reptiles probably 200 mya (e.g. Ichthyosaurs). The land reptiles were, of course, the dinosaurs. The biggest of them, i.e., Tyrannosaurus rex was about 20 feet in height and had huge fearsome dagger like teeth. About 65 mya, the dinosaurs suddenly disappeared from the earth. We do not know the true reason. Some say climatic changes killed them. Some say m