Each question is a logical sequence of statements with a missing link, the location of which is shown parenthetically. From the four choices available you are required to choose the one which best fits the sequence logically.
The question of what rights animals should enjoy is a vexatious one, Hundreds of millions of animals are put to death for human use each year. Contrariwise, it can be argued that slowing down scientific research would retard discovery of antidotes to diseases such as cancer which kill humans and animals alike. (_________). What if super intelligent beings from Alpha Centauri landed on earth and decided to use us for their experiments, arguing that they could save far more of their and our lives by so doing?