The correct answer is A. Sequence
Step-by-step explanation:
Words such as "first", "second", "third" or "finally" act as keywords or linking words in sentences or texts by allowing the reader to understand the connection between ideas. These words are especially used in sequences or to connect pieces of information that have a specific order, for example, you can use them to organize the steps in a recipe "First, add the egg; second, mix them with the flour and sugar; finally, put the dough into the oven". Therefore, the keyword "third" is mainly used for sequence.