Final answer:
Pea plants form a symbiotic association with a fungus called mycorrhizae.
Step-by-step explanation:
In a symbiotic association, pea plants form a mutualistic relationship with a fungus. This relationship is called mycorrhizae, where the fungal mycelia help the plant absorb water and minerals from the soil, while the plant supplies the fungus with the products of photosynthesis to sustain its metabolism. This association benefits both the fungus and the pea plant, aiding their survival and growth.