They are producers because they create their own food
The organism that is producer in the food web is Plant. These organism belongs to the group of autotrophic organism.
These organism use sunlight and convert it into chemical energy. This energy is used by producers and consumers to carry the various metabolic processes of the body.
Only producers have the ability to make food and hence, they do not depend on any other organism for their energy needs.
Hence, the correct answer is "option D".
before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.