The medium of instruction commonly used in government schools in Karnataka:

English
Hindi
Kannada
Varies from school to school

The correct answer is: D) Varies from school to school.

The medium of instruction in government schools in Karnataka varies from school to school. Some schools use Kannada as the medium of instruction, while others use English. There are also a few schools that use both Kannada and English as the medium of instruction. The medium of instruction is decided by the school management, and it is usually based on the needs of the students.

Kannada is the official language of Karnataka, and it is the language that is spoken by the majority of the people in the state. Therefore, it is not surprising that many government schools in Karnataka use Kannada as the medium of instruction. However, English is also a widely spoken language in Karnataka, and there are many schools that use English as the medium of instruction. This is especially true for schools that are located in urban areas.

There are also a few schools in Karnataka that use both Kannada and English as the medium of instruction. These schools are usually called bilingual schools. Bilingual schools offer a unique opportunity for students to learn two languages at the same time. This can be a great advantage for students who want to pursue higher education or employment in a globalized world.

The medium of instruction is an important decision that should be made carefully. It is important to consider the needs of the students, the resources available, and the goals of the school.