Subordinating conjunctions are transitions words that signal:

Subordinating conjunctions are transition words that signal the beginning of a subordinating clause. (A subordinate clause is a clause that depends on another clause and cannot stand alone.)

Examples of subordinating conjunctions are:

because, when, as, as long as, unless, until, after, before, although, provided that, etc.

There are 3 types of conjunctions:

The subordinating conjuctions can introduce:

your answer is c) experiments with water vapor showed that elements combine in specific proportions.

this answer to this question is c. allegory

why?

stories with allegories have a hidden symbolic meaning with a theme. the hidden meaning can be political, or other real life problems.