Sexual reproduction in Spirogyra is an advanced feature because it shows

Explanation

d. Sexual reproduction in Spirogyra is considered an advanced feature because it shows morphologically different sex organs. Spirogyra is a type of filamentous green alga that exhibits a well-defined sexual reproduction process involving male and female gametangia, which are morphologically distinct structures. The male gametangium (antheridium) produces non-motile male gametes, while the female gametangium (oogonium) produces non-motile eggs. This morphological differentiation is a more advanced form of sexual reproduction compared to species with isogamous gametes or less distinct sexual structures( correct option).Other options are explained below:a. Different sizes of motile sex organs:This option suggests the presence of different-sized motile sex organs in Spirogyra. However, Spirogyra exhibits isogamy, where the male and female gametes are of the same size. Additionally, Spirogyra does not have motile sex organs; instead, the isogametes are released into the water for fertilization.b. Same size of motile sex organs: This option is more accurate than the first one. Spirogyra's isogametes are indeed of the same size. However, it's important to note that Spirogyra lacks motile sex organs. The isogametes are released into the water and move passively to find each other for fertilization.c. Morphologically different sex organs: This option suggests the presence of morphologically different sex organs in Spirogyra. However, Spirogyra exhibits isogamy, where the male and female gametes are morphologically similar. The absence of morphological differences is a characteristic feature of isogamous reproduction.In summary, Spirogyra's sexual reproduction is characterized by isogamy, where the gametes are of the same size and lack morphological and physiological differentiation. Additionally, Spirogyra does not have motile sex organs; instead, the isogametes rely on water currents for fertilization.