The correct answer is: A. PQSR
The sentence is about the ongoing research for the development of an AIDS vaccine. The research is due to enter laboratory trials shortly, but this is not reason enough to relax the vigil against the killer disease.
The first option, PQSR, is the correct sequence. The sentence starts with the topic sentence, “The ongoing research for development of an AIDS vaccine is due to enter laboratory trials shortly.” This is followed by the reason for the research, “to relax the vigil against the killer disease.” The sentence ends with the conclusion, “is not reason enough.”
The second option, QSRP, is not the correct sequence. The sentence starts with the reason for the research, “to relax the vigil against the killer disease.” This is followed by the topic sentence, “The ongoing research for development of an AIDS vaccine is due to enter laboratory trials shortly.” The sentence ends with the conclusion, “is not reason enough.”
The third option, SQRP, is not the correct sequence. The sentence starts with the conclusion, “is not reason enough.” This is followed by the reason for the research, “to relax the vigil against the killer disease.” The sentence ends with the topic sentence, “The ongoing research for development of an AIDS vaccine is due to enter laboratory trials shortly.”
The fourth option, SRQP, is not the correct sequence. The sentence starts with the conclusion, “is not reason enough.” This is followed by the topic sentence, “The ongoing research for development of an AIDS vaccine is due to enter laboratory trials shortly.” The sentence ends with the reason for the research, “to relax the vigil against the killer disease.”