Out of the statements presented regarding the skeletal system, the last one would be the only true statement which says that there are 3 components to the sternum bone.
For the number of vertebrae that cover the spinal cord, there are around 31 segments that have it. For the pairs of ribs, there are 12 pairs of it. There are also 14 major facial bones. As for the components of the sternum bone, there are 3 components which are as follows: the manubrium, the body, and the xiphoid process.
Homozygous means "the same" and Heterozygous means "different". If a pheno type is homozygous, for example, it could be XX or xx, while heterozygous could be Xx. Hope that helps.
