The correct answer is option 2. Inactive Nitrogen and Argon gases are used in electric bulbs in order to increase the life of the filament.

Option 1, increasing the intensity of light emitted, is not the purpose of using these gases. In fact, the gases do not directly affect the brightness of the bulb.

Option 3, making the emitted light colored, is also not the purpose of using these gases. The gases do not alter the color of the light emitted by the bulb.

Option 4, making the production of the bulb economical, is not the reason for using these gases. The gases are chosen for their properties that help increase the lifespan of the bulb`s filament, rather than for economic reasons.

Inactive Nitrogen and Argon gases are chosen because they are chemically inert, meaning they do not react with the filament material. This prevents the filament from corroding or degrading over time, leading to a longer bulb life.