An example of a pioneer species is a- a sparrowb- a lichen c- an earthwormd- a spider

The right answer is Lichen.

In ecology, a pioneer species is one of the first forms of life that colonize or recolonize a given ecological area.

Lichens are composite organisms resulting from a symbiosis between at least one heterotrophic fungus called mycobionte, representing 90% of all, and microscopic cells with chlorophyll (green algae or cyanobacteria autotrophic for carbon) called "photobionts" .

the trilobite is used as an index fossil for various geologic time periods as specific types of the trilobites were present in different geological time periods. they are a group of marine arthropods belonging to the class of trilobita.

explanation:

the answers are as following:

1. c. double helix, nucleosome, coil, supercoil, chromosome

2. b. g2 phase, preparation for mitosis

3. d. interphase consists of the g1, s, and g2 phases

4. c. metaphase

5. a. chromosomes are duplicated before cell division so that each new daughter cell has a complete set