The correct answer is for.

The phrase "they argued for the right to strike" means that they were in favor of the right to strike. They were making a case for why the right to strike should be allowed.

The other options are not correct because they do not make sense in the context of the sentence.

• With would mean that they were arguing alongside the right to strike. This does not make sense because the right to strike is a concept, not a person.
• From would mean that they were arguing away from the right to strike. This does not make sense because the sentence says that they were arguing in favor of the right to strike.
• Against would mean that they were arguing against the right to strike. This is the opposite of what the sentence says.

Therefore, the correct answer is for.

Here are some examples of how the phrase "they argued for the right to strike" could be used in a sentence:

• The union argued for the right to strike, saying that it was essential for workers to be able to bargain collectively.
• The protesters argued for the right to strike, saying that it was a fundamental human right.
• The government argued against the right to strike, saying that it would harm the economy.