Correct option (a) several diatoms and a few cyanobacteria
Explanation:
Auxospores and hormocysts are formed by several diatoms and a few cyanobacteria respectively. Bacillariophyceae members (diatoms) are microscopic, eukaryotic, unicellular or colonial coccoid algae. These algae are sexually reproduced by the formation of auxospores in most cases. Bozi (1914) and Fermi (1930) reported that short sections of living cells at the tips of the trichomes of Wertiella Janosa become invested by a thick, lamellated, pigmented sheath. Such multicellular spore-like structures functions as perennating bodies. They are specially modified hormones and are called homosporous or hormocysts.