The word "bust" is the predicate adjective in the sentence " After a busy morning, the children were ready for their lunch". The correct option in regards to the question given is option "c". The reason being that the word "busy" modifies the subject of the sentence which is "children". It is very important to learn first the meaning of predicate adjective. Predicate adjective is the word that actually modifies the subject of the sentence. When there is a verb in the sentence, then a person can be sure that there will be a predicate adjective under most circumstances.
A transitional topic sentence is most often implied, although of course it should be noted that this is not always the case, and that it varies greatly with the speaker.
