To understand the coordination geometries around the copper ion of plastocyanin in oxidized and reduced forms, we need to delve into the structural characteristics of this blue-copper protein.

Plastocyanin is a type of protein that contains a single copper ion. It plays a crucial role in electron transfer during photosynthesis. The geometry around the copper center in plastocyanin is typically categorized under the class of ‘blue-copper’ proteins, known for their peculiar electronic and geometric properties.

In both oxidized and reduced forms, plastocyanin has a distorted tetrahedral geometry around the copper ion. Here's why:

1. Copper Coordination in Plastocyanin: The copper in plastocyanin is coordinated by two nitrogen atoms from histidine ligands, one sulfur atom from cysteine, and one sulfur atom from methionine. This arrangement forms a distorted tetrahedral geometry.
2. Oxidation States and Geometry: The copper can exist in the +1 or +2 oxidation state. However, the distortion in tetrahedral geometry remains consistent across these states. The geometry is termed 'distorted' due to slight deviations caused by the protein's 3D structure and the varying ligand field.

Given this understanding, the appropriate choice is:

Distorted tetrahedral for both oxidized and reduced forms.

Other options such as "tetrahedral and square-planar," "square-planar and tetrahedral," and "ideal tetrahedral for both" do not correctly describe the consistent geometrical distortion experienced by the copper center in plastocyanin.

Thus, the correct answer is indeed distorted tetrahedral for both.