The correct sequence of conductivity when arranged in ascending order is option 4: Insulators, semiconductors, metals.

Insulators, as the name suggests, are materials that do not conduct electricity easily. They have high resistance to the flow of electric current. Examples of insulators include rubber, glass, and plastics.

Semiconductors are materials that have moderate conductivity. They have properties between insulators and conductors. The conductivity of semiconductors can be altered or enhanced by introducing impurities or applying an electric field. Silicon and germanium are examples of commonly used semiconductors.

Metals are materials with the highest conductivity. They have a large number of free electrons that can move freely and conduct electric current. Metals such as copper, silver, and aluminum are excellent conductors of electricity.

Therefore, the correct sequence in ascending order of conductivity is insulators, semiconductors, and metals.