Why should you not touch the glass portion of a new light bulb?

Touching the glass portion of a new light bulb should be avoided primarily because it can cause the bulb to malfunction. When you touch the glass, you leave oils and residues from your skin on its surface. These contaminants can create hot spots when the bulb is lit, leading to uneven heating and potential overheating of the bulb. Over time, this can reduce the effectiveness of the bulb, even resulting in its premature failure.

While the other options mention various risks associated with handling light bulbs, they do not directly address the core issue at hand, which is the technical problem of malfunctioning due to oil residues. For example, while bulbs can break easily or cause injuries, the direct impact of touching the glass on the bulb's performance is a more significant reason to refrain from doing so. The concept of reducing the lifespan of the bulb goes hand in hand with malfunctioning but stems primarily from the issues created by the oils left on the glass itself.