SELECT t1.model FROM headphone AS t1 JOIN stock AS t2 ON t1.headphone_id  =  t2.headphone_id GROUP BY t1.model ORDER BY sum(t2.quantity) DESC LIMIT 1
Find the headphone model whose total quantity in stock is the largest.
CREATE TABLE "headphone" (
"Headphone_ID" int,
"Model" text,
"Class" text,
"Driver-matched_dB" real,
"Construction" text,
"Earpads" text,
"Price" int,
PRIMARY KEY ("Headphone_ID")
);
CREATE TABLE "store" (
"Store_ID" int,
"Name" text,
"Neighborhood" text,
"Parking" text,
"Date_Opened" text,
PRIMARY KEY ("Store_ID")
);
CREATE TABLE "stock" (
"Store_ID" int,
"Headphone_ID" int,
"Quantity" int,
PRIMARY KEY ("Store_ID","Headphone_ID"),
FOREIGN KEY (`Store_ID`) REFERENCES `store`(`Store_ID`),
FOREIGN KEY (`Headphone_ID`) REFERENCES `headphone`(`Headphone_ID`)
);
INSERT INTO  "headphone" VALUES (1,"iGrado","Prestige","0.1","Plastic","Comfort Pads","49");
INSERT INTO  "store" VALUES (1,"Laurel Canyon","Valley Village","None","October 29, 2005");
INSERT INTO  "stock" VALUES (1,6,100);