What is the primary method through which arthropods can carry pathogens?

Arthropods are known as vector organisms, and their primary method of carrying pathogens is through their movement from one host or location to another. This mobility allows them to pick up pathogens from infected hosts and subsequently spread those pathogens to new hosts.

When arthropods, such as mosquitoes or ticks, encounter a host, they can feed on the blood of that host, which may carry various pathogens. As they travel, these vectors can transport these pathogens over distances, leading to new infections in other hosts. This is particularly significant in the case of diseases such as malaria or Lyme disease, where the arthropod not only acts as a carrier but also as a facilitator in the disease transmission cycle.

The other answer choices do not represent the primary method of pathogen transmission by arthropods. Feeding on plant material does not relate to the transmission of pathogens to animals or humans. The exoskeleton might provide some level of protection or contamination, but it is not the mechanism for carrying pathogens. Additionally, while molting is a growth process for arthropods, it does not serve as a method for pathogen transport. Thus, the correct answer reflects the essential role of arthropod movement in the transmission of diseases.