Why are lesser house flies considered a nuisance?

Lesser house flies are considered a nuisance primarily because they can carry and transmit diseases through food contamination and may also cause myiasis, which is the infestation of living tissue by fly larvae. Their ability to breed quickly and thrive in various environments, especially in decaying organic matter, increases the risk of their presence in places where food is prepared or stored. This poses a serious health risk as they can transfer pathogens from feces or other contaminated surfaces to food, making them a public health concern. This makes option B the most accurate reason for their classification as a nuisance.

The other choices do not accurately reflect the characteristics or behaviors of lesser house flies. For instance, they do not aggressively attack humans, which makes the first choice incorrect. The third choice incorrectly suggests that they are only attracted to clean environments; however, lesser house flies thrive in unsanitary conditions, often found near waste. Lastly, while some may consider elements like appearance or disturbance to peace, these factors do not capture the public health implications caused by the flies, rendering the last choice irrelevant in the context of why they are deemed a nuisance.