Eka-aluminium and eka-silicon are two hypothetical elements predicted by Russian chemist Dmitri Mendeleev in the late 19th century. Mendeleev developed the periodic table of elements and noticed certain gaps in the table where elements with unknown properties should exist. He used his understanding of the periodic trends and properties of known elements to predict the existence and properties of these yet-to-be-discovered elements.

Eka-Aluminium:
- Eka-aluminium was predicted by Mendeleev to have properties similar to aluminium (Al), which is a light metal with atomic number 13.
- Based on its position in the periodic table, eka-aluminium was predicted to have an atomic number of 31 and similar chemical properties to aluminium.
- The element that Mendeleev predicted as eka-aluminium turned out to be gallium (Ga), which was discovered in 1875 by Paul Emile Lecoq de Boisbaudran. Gallium has atomic number 31 and shares many chemical properties with aluminium.

Eka-Silicon:
- Eka-silicon was predicted to have properties similar to silicon (Si), which is a non-metallic element with atomic number 14.
- Mendeleev predicted eka-silicon to have an atomic number of 32 and similar chemical properties to silicon.
- The element that Mendeleev predicted as eka-silicon turned out to be germanium (Ge), which was discovered in 1886 by Clemens Winkler. Germanium has atomic number 32 and shares many chemical properties with silicon.

Explanation of the Correct Answer:
- The correct answer is option 'A', which states that eka-aluminium and eka-silicon are known as gallium and germanium, respectively.
- This answer is correct because gallium (eka-aluminium) and germanium (eka-silicon) are the elements that were discovered and found to have properties similar to those predicted by Mendeleev for eka-aluminium and eka-silicon.
- The other options, such as aluminium and silicon, iron and sulphur, and proton and silicon, do not correspond to the elements predicted by Mendeleev.

In conclusion, eka-aluminium and eka-silicon are known as gallium and germanium, respectively. These elements were predicted by Mendeleev based on their positions in the periodic table and were later discovered and found to have properties similar to those predicted.