Choose the best option to complete each sentence

I. Choose the best option to complete each sentence
1. We are talking about the writer ______ latest book is one of the best-sellers this year.
     A. which    B. whose        C. whom        D. who
2. He bought all the books ______ are needed for the English course.
    A. that        B. what        C. those         D. whose
3. The children, ______ parents work late, are taken home by bus.
    A. that        B. whom        C. whose        D. their
4. Our hotel, ______ is converted 17th century manor house, is very comfortable
    A. which    B. that            C. where        D. when