Rather than having true roots, stems and leaves the members of Phaeophyceae have root like holdfast, stem like stipe and leaf like fronds. What will be true for these structures?

I. Holdfasts are not the primary organs for water and nutrient uptake.
II. In brown algae like Fucus, the tissues in stipe include a central pith, a surrounding cortex and an outer epidermis.
III. Gas filled floats called pnematocysts provide buoyancy in many brown algae.

1. I and II only
2. I and III only
3. II and III only
4. I, II and III