Answer:
d. all of the offspring have medium length fur.
Explanation:
Incomplete dominance is a phenomenon in which offspring produce a trait that is intermediate between the two forms of a certain trait.
For example: In four o clock plant, some plants produce red flowers while some plants produce white flowers. When plants with red flowers are crossed with plants with white flowers, all the offspring have pink flowers.
Why is that so?
This is because no allele is completely dominant over the other and therefore both contribute their individual effect by producing intermediate phenotype.
Example in question:
Cross between a rabbit with short fur (SS) and a rabbit with long fur (LL)
P1: SS x LL
Gametes: S and L
Offspring SL :SL
SL: Medium length fur
Therefore this is a case of incomplete dominance.
Hope it help!