The question pertains to geology, specifically the composition of sandstone. In geological terminology, sandstone can contain various materials in its matrix or within its pores, which affect how it forms and behaves.

The correct answer to the question is "Pseudomatrix." A pseudomatrix is a type of material formed in sandstones where weak detrital grains have been deformed and aligned within pore spaces, typically due to compaction or pressure dissolution processes. This results in a discontinuous matrix-like appearance.

1. Orthomatrix: This term isn't commonly used in geological literature; hence, it can be ruled out as it doesn't describe the material formed by the squeezing of detrital grains.
2. Epimatrix: Epimatrix usually refers to a secondary matrix in geological formations, not specifically related to the formation process described in the question.
3. Protomatrix: Protomatrix can describe original cement or binding material in sedimentary rocks but not the deformation of weak grains.
4. Pseudomatrix: This is the correct term. It accurately describes the deformed and aligned weak grains in sandstone pore spaces.

Therefore, considering the options and geological definitions, "Pseudomatrix" is the appropriate choice. It is important for students preparing for geology-related exams to understand these terms and their correct applications as they are fundamental in identifying and understanding sedimentary rock formations.