单选题 One of the major problems most small businesses encounter today is ______ advertising is often costly and often takes some time to begin working.

(A) because
(B) that
(C) What
(D) how

【正确答案】 B

【答案解析】[理由] 本句分析如下：
One of the major problems most (1)
small businesses encounter (2)
today is that advertising is (3)
often costly and often takes some time to begin working(4)
(1)为主语。
(2)为定语从句，之前有关系代词which，代替先行词one of the major problems。由于which在此定语从句中作及物动词encounter(遭遇)的宾语，故可省略。
(3)为本句的动词。
(4)为that引导的名词从句，作表语。
根据上述，(B)应为正选。