A producer is an organism that produces its own energy (complex molecules from simple molecules) via photosynthesis or chemosynthesis.
D, the rest of the options are all consumers that eat producers. Plants are producers since they photosynthesise to transfer their energy, they do not require eating anything therefore they are producers. The consumers eat plants to get their energy (energy is transferred from the producer to the consumer).
This is an example of acquired mutation in which there is genetic transformation due to external factors such a change of temperature, pollution, radiation etc.