Which four flies are known to bite humans?

The four flies known to bite humans are indeed the stable fly, horse fly, black fly, and deer fly. Each of these species is recognized for their ability to deliver painful bites, which can lead to discomfort and, in some cases, trigger allergic reactions in sensitive individuals.

Stable flies are notorious for biting livestock but will also bite humans, while horse flies are known for their strong, painful bites due to their sharp mouthparts, which they use to cut into skin. Black flies, often found near running water, are also infamous for their biting behavior, as they require blood meals for reproduction. Lastly, deer flies, which are similar in appearance to horse flies, also use their biting ability to obtain blood, primarily to nourish their larvae.

In contrast, the other fly types mentioned in the other options—like house flies, face flies, bottle flies, blow flies, cluster flies, moth flies, and fruit flies—are not known for biting humans. While some may carry diseases or be nuisances, they do not exhibit biting behavior. This distinction makes option C the correct choice in identifying flies that pose a biting risk to humans.