The word that can be best used to complete the sentence is "the most" as it shows an adjective of degree.
Therefore, the complete sentence would be: Firefighting is one of the most dangerous jobs in the world.
This refers to the comparison that is used to show the relationship or severity of a situation in a sentence.
Hence, we can see that the three degrees of adjectives are:
Read more about adjective of degree here:
https://brainly.com/question/22480408
#SPJ1