The correct answer is D. sometimes inverted and sometimes upright.
A food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another. The number of organisms at each trophic level (feeding level) typically decreases as you move up the food chain. This is because energy is lost at each trophic level as some of it is used for respiration and other metabolic processes.
In a parasitic food chain, the parasite is the consumer and the host is the resource. Parasites typically have a much smaller body size than their hosts, so the pyramid of numbers in a parasitic food chain is often inverted. This is because there are typically many more hosts than parasites.
However, there are some cases where the pyramid of numbers in a parasitic food chain can be upright. This is most likely to occur when the parasite is a large animal that preys on small animals. For example, a lion is a large predator that eats zebras, which are much smaller animals. In this case, the pyramid of numbers would be upright because there are fewer lions than zebras.
Ultimately, the shape of the pyramid of numbers in a parasitic food chain depends on the specific interactions between the parasite and its host.