Which of the following statements about algae is/are correct? (i) Algae are chlorophyll – bearing simple, thalloid, heterotrophic and aquatic (both fresh water and marine) organisms. (ii) Algae reproduce by vegetative means only. (iii) Fusion of two gametes dissimilar in size is termed as isogamous. (iv) A few of the massive forms of algae such as kelps, form massive plant bodies.