Read the sentence to find out if there is any error in it. The error, if any, will be in one part of the sentence. The number of that part will be the answer. If there is no error, then the answer is (E). Ignore error of punctuation if any.

Historically and strategically, the northern portion (A)/ of an Indian Ocean is considered very (B)/ im­portant because it is accessible from the (C)/ west and the east only through narrow straits. (D)/ No error (E)