[求助]大全30

30.A special Japanese green tea called genmai-cha contains brown rice and is considered as a delicacy fit for a gourmet by most Japanese, though it is virtually unavailable outside Yokohama.
(A) A special Japanese green tea called genmai-cha contains brown rice and is considered as a delicacy fit for a gourmet by most Japanese, though it is virtually unavailable outside Yokohama.
(B) Considered to be a delicacy fit for a gourmet by most Japanese, genmai-cha is a special green tea that contains brown rice, virtually unavailable outside Yokohama.
(C) A special Japanese green tea called genmai-cha contains brown rice and is considered a gourmet delicacy by most Japanese, though it is virtually unavailable outside Yokohama.
(D) Most Japanese consider genmai-cha, a special green tea which contains brown rice, as a delicacy virtually unavailable outside Yokohama.
(E) Though virtually unavailable outside Yokohama, most Japanese consider genmai-cha, a special green tea that contains brown rice, a gourmet delicacy.

[C]

请问各位NN，B为什么不对？错在什么地方了，谢谢指教～

我也选的B，能再解释清楚点吗？

sth was considered to be sth

to be 一定要省略