Final answer:
Cat litter pans and gardening are sources for the protozoan Toxoplasma gondii, which causes toxoplasmosis, particularly through contact with infected cat feces.
Step-by-step explanation:
Cat litter pans and gardening are sources for the protozoan Toxoplasma gondii, which causes toxoplasmosis. This parasite is found in a variety of birds and mammals, but domestic cats are the only definitive hosts for the sexual stages of T. gondii, making them the main reservoir for infection. Humans typically become infected through contact with cat feces in litter boxes or garden beds where cats might defecate, through unwashed fruits and vegetables, or from undercooked meat containing T. gondii.