What Did Experiments with the Brown Alga Fucus Help to Determine

What did experiments with the brown alga Fucus help to determine?

A) The cytoplasm is evenly distributed throughout the algal zygote.
B) The thallus anchors the alga to the surface on which it lives.
C) Light and gravity do not affect rhizoid orientation.
D) Magnesium gradients are important for cell wall formation.
E) A cell wall is required for the zygote to "remember" where a rhizoid should form.