In this task, you're given a question, along with a context passage which has extra information available on certain terms mentioned in it. Your job is to determine which sentence(s) from the passage can be used to search for further information needed to answer the question.

Let me give you an example: Question: When did the operation during which the 704th dropped supplies to allied troops near Nijmegen begin? Passage: The group was occasionally diverted from strategic missions to carry out air support and interdiction missions. It supported Operation Overlord, the invasion of Normandy by attacking transportation targets, including bridges, along with airfields and strong points in France. On D Day, the squadron and the rest of the 446th Group led the first heavy bomber mission of the day. The 446th aided ground forces at Caen and Saint-Lô during July by hitting bridges, gun batteries, and enemy troops. During Operation Market Garden, the attempt to seize a bridgehead across the Rhine in the Netherlands, the 704th dropped supplies to allied troops near Nijmegen. It struck lines of communications during the Battle of the Bulge. During Operation Varsity in March 1945, it supplied ground and airborne troops near Wesel. The squadron flew its last combat mission on 25 April 1945 against Salzburg, Austria. The group had flown 273 missions and had lost 58 aircraft during the war,
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The answer to this example can be: During Operation Market Garden, the attempt to seize a bridgehead across the Rhine in the Netherlands, the 704th dropped supplies to allied troops near Nijmegen.
Here is why: The passage describes the 704th's actions during Operation Market Garden.

OK. solve this:
Question: How many students were enrolled at Institut National Agronomique Paris-Grignon the year that Houellebecq began attending? Passage:Houellebecq was born in 1956 on the French island of Réunion, the son of Lucie Ceccaldi, a French doctor born in Algeria of Corsican descent, and René Thomas, a ski instructor and mountain guide. He lived in Algeria from the age of five months until 1961, with his maternal grandmother. In a lengthy autobiographical article published on his website (now defunct), he states that his parents "lost interest in [his] existence pretty quickly", and at the age of six, he was sent to France to live with his paternal grandmother, a communist, while his mother left to live a hippie lifestyle in Brazil with her recent boyfriend. His grandmother's maiden name was Houellebecq, which he took as his pen name. Later, he went to Lycée Henri Moissan, a high school at Meaux in the north-east of Paris, as a boarder. He then went to Lycée Chaptal in Paris to follow preparation courses in order to qualify for grandes écoles (elite schools). He began attending the Institut National Agronomique Paris-Grignon in 1975. He started a literary review called Karamazov (named after Fyodor Dostoevsky's last novel) and wrote poetry.

Answer:
He began attending the Institut National Agronomique Paris-Grignon in 1975