In this scenario, E.coli is living in our intestines, which means we are providing them with a place to live and nutrients to survive. It is also stated that they help us break down some foods.
so as you can see, we benefit them, and they benefit us.
Based on this, after defining all of your options, you will find your answer.
Asexual reproduction im thinking
There would be 2 dwarf(homozygous recessive)and 2 tall (heterozygous dominant)offsprings.
1) As blood groups A and B are equally dominant so the individual will express both characteristics in the phenotype.
Notice how in all the 3 other examples the organism is only expensive 1 version (allele) of each gene. For example the mouse with brown fur may have 2 brown fur alleles (and so would have to express this characteristic even if it was recessive) but it could have 1 allele which is less dominant than the brown, in which case brown would be expressed. In this case the alleles were not co-dominant.