Microtubules are one of the cytoskeletal filament systems in eukaryotic cells. The microtubule cytoskeleton is involved in the transport of material within cells, carried out by motor proteins that move on the surface of the microtubule.
Hope this helps you!
It is the last one, letter D.
R R
-----------
W | RW RW
W | RW RW
0% Homozygous
0% Recessive
100% Heterozygous
Genotype: RW
Phenotype: Red flower
So the answer is that none of them is dominant.