To what phylum do the horsehair/gordian worms belong?

In the life cycle of Enterobius vermicularis, where do the adult worms live?

To what domain do the echinoderms belong?

What is the scientific name of the roundworm that causes elephantiasis?

I conduct a study on the effect of a low carb diet on weight loss among people with a mobility issue. I use their weight that was recorded in the OT hospital clinic today and then measure their weight using my bathroom scale form home 4 weeks later. This could cause a threat to internal validity known as:

Look at the image below. The posterior end of two roundworms (Ascaris lumbricoides) is shown below. What is the gender of worm labeled #A?  

Which of the following is CORRECT concerning echinoderms?

In the life cycle of Wuchereria bancrofti, how is the host infected?

What type of appendages do arthropods have?

In the life cycle of Dirofilaria immitis, what system is affected by the infection?