What type of container has an elongated neck and is made of glass?

An ampule is characterized by its elongated neck and is primarily made of glass. This design serves a specific purpose: the neck of the ampule is typically sealed by heating, ensuring that the contents are protected from contamination and degradation. Ampules are commonly used for storing sensitive liquids, such as injectable medications or laboratory samples, which require a sterile environment.

The structure of the ampule allows for easy breaking at the neck to access its contents, making it suitable for single-use situations. This one-time opening is crucial since it prevents any potential for contamination after the seal is broken.

The other options, while also types of containers, do not feature the distinctive elongated neck and glass material that characterize ampules. Vials, for instance, are designed with a different shape and often have a rubber stopper for multi-use, while bags and jars serve different storage purposes and are not primarily specialized for sensitive liquids in the same way as ampules. Thus, the identifying characteristics of the ampule validate it as the correct choice.