Correct Option: A

Heterospory is considered important in the development of seed habit. Heterospory is the production of spores of two different sizes and sexes by the sporophytes of land plants. Heterospory was evolved from isospory independently by several plant groups in the Devonian period as part of the process of evolution of the timing of sex differentiation. Heterosporic plants produce small spores called microspores which either germinate to become male gametophytes or have reduced male gametophytes packaged within them, and similarly larger spores called megaspores that germinate into female gametophytes, or which have female gametophytes packaged within them.