The best way to distinguish between sedimentary, metamorphic, or igneous rock is to
hit it with a hammer
examine it with a magnifying glass
poor acid on it
rub it against a streak plate

look at this it will give you up to 17 answers  

answer; three;

producers within ecosystems are essential as they are at the base of the food chain. plants are examples of producers. they use the process of photosynthesis to capture light energy and use it to convert simple inorganic substances (carbon dioxide and water) into organic substances (glucose).