The answer to this question is 4. The level of this food pyramid that represents the largest amount of organisms would have to be the producers. Although this question may have tricked you, it is the producers who always have the highest number of organisms in the food pyramid. In order for consumers to be consumers, they must have producers who product things for them to consume.
Consumers can not thrive or even exist without the producers. So the tertiary consumers and the secondary consumers would not be there if there was no food to eat. The tertiary consumers are the ones that make sure that there is enough food for the other consumers.
Producers have the most number of amount in the food pyramid. Even in real life, this is considered to be true. There should be a lot of producers available for the primary consumers to thrive. Without producers, the primary consumers will cease to exist which means that secondary consumers and tertiary consumers would be gone as well because there is not enough food to eat.
Usually, it is the tertiary consumers that help in improving the number of producers. No matter which way you would look at it, all members of the food pyramid is important because they have their own roles to play to make the cycle of life go on.