New York, being the largest city in the United States, was 19 the 212 area code, followed by Los Angeles at 213.
答案：(B) assigned
be assigned sth 意為「被分配到某物」，本句指紐約因為是美國最大城而被分配到 212 這組區碼；reserved（保留，須用 be reserved for）、represented（代表）、assembled（組裝、集合）語意都不合。
assign sb sth（分配某物給某人）。看到 New York was assigned the 212 area code（紐約被分配到 212 這組區碼），被動後面還跟著一個名詞，你會覺得不通——那是 sth 那一格，原本就在那裡。assign 有兩個受詞，人一個、物一個。
兩個受詞的動詞改成被動，用人（間接受詞）當主詞，物（直接受詞）留在動詞後面不動，所以句子看起來會多一個名詞。這條路你國中走過：give sb sth 改成被動就是 The winner was given a prize.（優勝者獲頒一份獎品。）offer、send、award 全是同一組。語意也對得上：前一句說區碼是依人口規則分派的，本句接著說紐約分到 212、洛杉磯 213，一組一組發下去，正是「分配」。assign 家族一起記：assign（分配）、assignment（作業、任務）、an assigned seat（指定座位）、an assigned task（分派到的工作）。一句記完：The new crew members were assigned the busiest street in town.（新進的隊員被分配到鎮上最忙的那條街。）〔情境取材自 105 指考作文題：碩士考清潔隊員〕
reserved（保留）要接 for：be reserved for VIPs（保留給貴賓）；represented 是「代表」，區碼確實代表地區，但本句主詞是紐約不是號碼，方向反了；assembled 是「組裝、集合」，與號碼無關。
be assigned sth（被分配到某物）、be given／offered／awarded sth（被給予／提供／頒授某物）、be reserved for（保留給…）、an assignment（作業、任務）。
An area code is a section of a telephone number which generally represents the geographical area that the phone receiving the call is based in. It is the two or three digits just before the local number. If the number 16 is in the same area as the number making the call, an area code usually doesn't need to be dialed. The local number, 17 , must always be dialed in its entirety.
The area code was introduced in the United States in 1947. It was created 18 the format of XYX, with X being any number between 2-9 and Y being either 1 or 0. Cities and areas with higher populations would have a smaller first and third digit, and 1 as the center digit. New York, being the largest city in the United States, was 19 the 212 area code, followed by Los Angeles at 213.
In countries other than the United States and Canada, the area code generally determines the 20 of a call. Calls within an area code and often a small group of neighboring area codes are normally charged at a lower rate than outside the area code.