Which of the following flies is primarily associated with decomposing organic matter?

The flesh fly is primarily associated with decomposing organic matter due to its reproductive habits. The female flesh fly typically lays her eggs in decaying animal remains or other organic matter, where the larvae can feed on the decomposing tissues. This behavior not only aids in the breakdown of organic matter within the ecosystem but also makes flesh flies important forensic indicators in cases of crimes involving decomposition.

While other flies, such as horse flies, face flies, and stable flies, are associated with various habitats and behaviors, they do not primarily target decomposing organic material for their reproductive needs. For instance, horse flies are more attracted to livestock and are known for their biting habits, while face flies typically feed on the secretions of livestock, and stable flies are more associated with decaying vegetation and animal waste. None of these exhibit the same degree of association with decomposing organic matter as the flesh fly does.