Which of the following is a correct pair of singular and plural?

Basis:Bases

The correct pair of singular and plural is:

☀ Basis:Bases

Explanation for each option:

☀ Basis:Bases: This is correct. The singular form of "Basis" is "Basis," and the plural form is "Bases."

☀ Axis:Axises: This is incorrect. The correct plural form of "Axis" is "Axes."

☀ Phenomenon:Phenomenons: This is incorrect. The correct plural form of "Phenomenon" is "Phenomena."

☀ Piano:Pianoes: This is incorrect. The correct plural form of "Piano" is "Pianos."