user: You are a structured reasoning expert tasked with solving problems step by step. 
You first think about the reasoning process in the mind and then provide the answer. The reasoning process and answer should be enclosed within <think> </think> and <answer> </answer> tags, respectively, i.e., <think> reasoning process here </think> <answer> answer here </answer>. 
Given a question and the associated knowledge graph triplets (entity, relation, entity), you are asked to answer the question with these triplets and your own knowledge. 
You can break down the original question into several sub-questions and explore the given knowledge graph to solve them step-by-step. If there are multiple possible answers, choose one as the final answer. 
After thinking, when you finally reach a conclusion, clearly state the answer within <answer> </answer> tags, i.e., <answer> answer here </answer>. 
Question: which is the video game series that includes a video game expansion designed by mike darga? 
Knowledge Triplets: The Sims 2: Pets, base.wikipedia_infobox.video_game.platforms, Microsoft Windows
The Sims 2: Pets, cvg.computer_videogame.publisher, Aspyr
The Sims 2: Pets, cvg.computer_videogame.developer, EA Mobile
The Sims 2: Pets, cvg.computer_videogame.cvg_genre, Life simulation
Life simulation, cvg.cvg_genre.games, The Sims 2: Pets
The Sims 2: Pets, imdb.topic.title_id, tt0872267
The Sims 2: Pets, base.wikipedia_infobox.video_game.developer, Maxis
Lakshmi Jalapayan, cvg.cvg_designer.games_designed, The Sims 2: Pets
The Sims 2: Pets, cvg.computer_videogame.developer, Maxis
The Sims 2: Pets, base.wikipedia_infobox.video_game.platforms, Game Boy Advance
Electronic Arts, cvg.cvg_publisher.games_published, The Sims 2: Pets
God game, cvg.cvg_genre.games, The Sims 2: Pets
Maxis, cvg.cvg_developer.games_developed, The Sims 2: Pets
Charles London, cvg.cvg_designer.games_designed, The Sims 2: Pets
The Sims 2: Pets, base.wikipedia_infobox.video_game.platforms, PlayStation 2
The Sims 2: Pets, cvg.computer_videogame.gameplay_modes, Single-player video game
The Sims 2: Pets, user.avh.default_domain.ellerdale_topic.ellerdale_id, 0088-7ea8
The Sims 2: Pets, base.wikipedia_infobox.video_game.developer, EA Mobile
The Sims 2: Pets, base.wikipedia_infobox.video_game.platforms, Mac OS
Mike Darga, cvg.computer_videogame.designers, The Sims 2: Pets
The Sims 2: Pets, cvg.computer_videogame.publisher, Electronic Arts
The Sims 2: Pets, base.wikipedia_infobox.video_game.platforms, Nintendo DS
The Sims 2: Pets, cvg.computer_videogame.cvg_genre, Role-playing video game
Strategy video game, cvg.cvg_genre.games, The Sims 2: Pets
Electronic Arts, cvg.cvg_developer.games_developed, The Sims 2: Pets
Simulation video game, cvg.cvg_genre.games, The Sims 2: Pets
The Sims 2: Pets, cvg.computer_videogame.release_date, 2006-10-17
The Sims 2: Pets, cvg.computer_videogame.cvg_genre, God game
The Sims 2: Pets, cvg.computer_videogame.designers, Mike Darga
The Sims 2: Pets, cvg.computer_videogame.designers, Lakshmi Jalapayan
Aspyr, cvg.cvg_publisher.games_published, The Sims 2: Pets
The Sims 2: Pets, cvg.computer_videogame.cvg_genre, Simulation video game
The Sims 2: Pets, cvg.computer_game_expansion.expansion_for, The Sims 2
The Sims 2: Pets, cvg.computer_videogame.designers, Hunter Howe
Hunter Howe, cvg.cvg_designer.games_designed, The Sims 2: Pets
The Sims 2: Pets, cvg.computer_videogame.designers, Charles London
Amaze Entertainment, cvg.cvg_developer.games_developed, The Sims 2: Pets
The Sims, cvg.game_series.games_in_series, The Sims 2: Pets
The Sims 2: Pets, cvg.computer_videogame.developer, Amaze Entertainment
The Sims 2, cvg.computer_videogame.expansions, The Sims 2: Pets
The Sims 2: Pets, cvg.computer_videogame.game_series, The Sims
The Sims 2: Pets, cvg.computer_videogame.developer, Electronic Arts
Role-playing video game, cvg.cvg_genre.games, The Sims 2: Pets
m.0r3h81w, dataworld.gardening_hint.last_referenced_by, The Sims 2: Pets
The Sims 2: Pets, cvg.computer_videogame.versions, The Sims 2: Pets
The Sims 2: Pets, cvg.computer_videogame.cvg_genre, Strategy video game
Single-player video game, cvg.gameplay_mode.games_with_this_mode, The Sims 2: Pets
The Sims 2: Pets, base.wikipedia_infobox.video_game.platforms, GameCube
Mike Darga, cvg.cvg_designer.games_designed, The Sims 2: Pets
EA Mobile, cvg.cvg_developer.games_developed, The Sims 2: Pets
The Sims 2: Pets, base.wikipedia_infobox.video_game.platforms, PlayStation Portable
The Sims 2: Pets, base.wikipedia_infobox.video_game.platforms, Wii
The Sims 2: Pets, cvg.game_version.game, The Sims 2: Pets
The Sims 2: Pets, cvg.game_series.games_in_series, The Sims

Answer: The Sims