Select the correct passive form of the given sentence.
This book explores the secret of leading a long and meaningful life

Options

A. The secret of leading a long and meaningful life is explored in this book.
B. The secret of leading a long and meaningful life was being explored by this book.
C. The secret of leading a long and meaningful life have been explored by this book.
D. The secret of leading a long and meaningful life had been explored by this book

Explanation

(a) The thieves were arrested yesterday by the police. (Correct) (b) The thieves have been arrested yesterday by the police. (Tense has changed) (c) The thieves were being arrested yesterday by the police. (Tense has changed) (d) The thieves had been arrested yesterday by the police. (Tense has changed)