A dramatic irony is usually found in a book like drama you know what is happening but the main character doesn't know
The first word in the sentence is a pronoun- not an adjective.
The second option - Australian is in fact an adjective, it gives some information about the terrier.
the second option - children - is a noun, so it is not an adjective.
And the last option is a verb,
So the correct answer is B - this is the only adjective.
Add answer choices because without i cant help you just re-post it with answer choices
Adjunct,affix,annex,adhere?