肿瘤的实质由透明细胞组成的是（）

A.乳腺髓样癌

B.肝细胞癌

C.直肠腺癌

D.胃黏液癌

E.肾细胞癌

_____ this is only a small town, it's crowded with tourists who come here all year round.[ ]

A. Since

B. Although

C. As though

D. Unless