The correct answer is: hyphae
Hyphae are long filamentous structures of the fungi responsible for the growth. Hypha branched and grouped together are called mycellium. Besides the growth hypha are involved in nutrition. For example, parasitic fungi have specialized hyphae for nutrient absorption within a specific host. Another example, arbuscules- specialized form of hyphae found in the roots of some vascular plants which absorb nutrients and water from the soil.
