Answer:
a. reliquary
Step-by-step explanation:
Reliquary is a container for a relic, a historical or sacred item. In religious institutions, they usually hold and present some items connected to the beliefs or the saints, most likely bones or items of clothing. They are frequent in Christianity, but also in Buddhism and Hinduism. The one presented here is likely Christian - we can dedicate this by the form and the decoration in the shape of angels.
As the items are considered to be priceless, the containers are also made to be very crafty and worthy. They are likely done in precious metals (gold or silver) and decorated with gems.
They are often done in the form of the glass box, like the one presented here, but they can take various forms. The most popular forms are the true cross, church, philatory, and the monstrance.