Which group represents a low symmetry group?

The group Ci represents a low symmetry group because it consists of only a single improper rotation operation (a center of inversion) and does not possess any rotational or reflection symmetry elements beyond this. In symmetry group notation, Ci indicates a very simple and low-order symmetry, reflecting the minimal constraints on the arrangement of atoms in a molecule.

In contrast, the other groups have higher symmetry. The Oh group corresponds to octahedral symmetry, which features multiple axes of rotation and mirror planes, giving it a high degree of symmetry. The Td group, which represents tetrahedral symmetry, also includes several rotational symmetry elements, making it more symmetrical than Ci. Finally, the Ih group denotes icosahedral symmetry, known for its high level of symmetry with multiple rotational axes and planes of symmetry.

The simplicity of the Ci group makes it the representative of low symmetry in this context, as it has the least amount of symmetry operations available compared to the other listed groups.