The most accurate response would be:
a The properties will likely be different because the repeating groups of atoms that make up each sample are different.
This option emphasizes that the differences in the arrangement and types of atoms in the repeating groups can lead to varying physical and chemical properties, which influences smell, color, melting temperature, and other characteristics. The other options incorrectly attribute property similarities or differences to the number of groups or the presence of some common atoms without considering the overall molecular structure.