Select the option which is the most appropriate one word substitution for the given group of words.

That which cannot be seen through

opaque

The most appropriate one-word substitution for the given group of words "that which cannot be seen through" is opaque.

Transparent means that which can be seen through easily.

Translucent means that which can be seen through but not clearly.

Impervious means that which cannot be penetrated or affected.

The word opaque is the most appropriate because it specifically refers to something that cannot be seen through at all. The other words do not have the same connotation of complete opacity.