The answer to this question is the Pyers
patches. The Pyers patches are lymphatic tissues found through
the small intestines that have an important role in the immune system. Pyers
patches are also known as the aggregated lymphoid nodules that monitors and
prevents growth of bacteria in the intestine that is harmful in the intestines.
Answer:

Explanation:
We recognize that total occurrence equals new cases of disease over time divided by the number of people at risk at the onset.
Mathematically:

Given that:
Number of the population at risk = 1000 individuals
New cases during Jan 1 - Dec 31 = 60 because;
At 20 occurred on June 30 & 40 on Sept. 30) & no new cases were identified after that:
∴

B: receptor, sensory, interneuron, motor, effector