A "conduit" is a pipe; an injury is a temporary physical disability; a residence is a home; a hedonist is a person who seeks pleasure; and propensity means a tendency.

A "klaxon" is a loud electric horn typically used as a warning signal. So, the best answer choice is "alarm," which means a noise that is used to warn of danger. Considering the other answer choices, "shout" means yell, "crash" means collide or impact, "concern" means worry, and "crisis" means catastrophe or emergency.

The best answer is "decorations". The word "regalia" usually refers to royal possesions which are very decorative. They can include ceremonial clothes, designs, or emblems. "Clothes" simply refers to garments or apparel. The defining characteristic of regalia is that is is very decorative, and the word clothes does not imply this meaning. The word "regions" is unrelated, and the remaining words, "fancy" and "royalty," are words one might use when talking about "regalia," but are not "regalia" themselves. 

A synonym for "memento" is "keepsake," which means something special that reminds someone of something. A "bracelet" or "toy" can each be a memento, while an "heir" can be someone who inherits some type of memento, but none of these words mean "memento." The word "money" is unrelated.

"Shanty" is a shack or small hut. "Omen" is a sign or warning of the future. "Etiquette" is socially accepted manners or customs. "Messenger" is a person who delivers letters and messages. "Abyss" is a deep hole or gap.

A “cavity” is a hole or hollow space (usually used to describe a hole in a tooth). The correct answer is “void” which also means emptiness, lacking in something.

The words "edifice" (or building) and "structure" are synonymous nouns referring to a built object or building. The other words do not have similar meanings.

"Solid" and "concrete" are synonyms referring to objects that are firm and in an unchanging shape. The other words do not have relevant meanings. "Aquatic" and "marine" both refer to objects that are related to water. "Naval" refers to actions or objects related to the navy. 

A "refuge" is a sanctuary or asylum, a safe place to stay. An "abode" is a home (for people), while an "aviary" is a structure that houses birds. A "schoolhouse" is a building in which people (usually children) are educated. While "refugees" are often seen at campsites, a "campground" is not necessarily a "refuge."

A "melee" is a brawl or a physical fight. A "treaty," on the other hand, is a peace agreement. A "meal" is something eaten (breakfast, lunch, or dinner), and a "document" is a piece of paper on which there is writing or text. A "roadway" is a street or path.