In the following passage, some of the words have been left out. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.
That is why publicly invoking these symbols has to be an act of responsible citizenship and not self-serving demagoguery, but the difference can be hard to tell. The problem with emotive symbols is that _________ they can multiply the force of arguments, they cannot replace the arguments _________ debated. All persuasion harnesses symbols but principled persuasion must also provide arguments that can be _________.

The problem with emotive symbols is that _________ they can multiply the force of arguments,

1. A
   tough
2. B
   though
3. C
   through
4. D
   Thorough