How is an index contour usually indicated?

Contour lines are described as the places having equal elevation and they never intersect one another.

The index contours are the contour lines that are usually highlighted by a thicker contours, dark in color and they are shown as every fifth contours. The height of these contours are mentioned in numbers adjacent to these lines. The presence of index contours makes it easy to understand the topography of an area.

well for one plants are always the producer, so a is the answer. a wolf is more of the consumer(predator) and the deer is the prey so i know those two are out of the question. also mushrooms are fungi/fungus so a is the producer.