Which of the following is true? Question 12 options:

1. Most organisms present early in Earth's prehistory were more complex than modern organisms.
2. Species on Earth today are but a fraction of all species that ever lived.
3. The number of species existing at one time has decreased throughout history.
4. Extinctions of past species have always happened gradually and on a small scale.
5. Bacteria represent a newer form of life, not present during the early prehistory of Earth.