Final answer:
The oak tree is the producer among the given options, as producers are organisms that can synthesize their own food through processes like photosynthesis.
Step-by-step explanation:
Among the options provided, the oak tree is considered the producer. Producers, also known as autotrophs, are living organisms that create their own food typically through photosynthesis, using sunlight to convert carbon dioxide and water into organic compounds. An oak tree is a plant that performs this process, hence making it a producer. This is in contrast to animals like raccoons, cockroaches, and humans, that are considered consumers because they cannot produce their own food and rely on other organisms for sustenance.