In the following sentence, a part of the sentence is underlined. Below are given alternatives to the underlined part, which may improve the sentence. Choose the correct alternative. In case no improvement is needed, choose the alternative that indicates 'No improvement.'
The Portuguese began to explore a west coast of Africa.
1
Begin to explore a
2
Are beginning to explore a
3
Began to explore the
4
No improvement
5
None of the above