P. In November of that year, a portion of the battlefield was dedicate
Q. The chief speech on that occasion was given by Edward Everett, a celebrated orator.
R. One of the most terrible battles of the American Civil War was fought in July 1863, at Gettysburg.
S. Lincoln was asked to make a few remarks.
Right Answer is: B
Sentence R will be the opening statement as it introduces the subject of the sequence i.e. American Civil War of 1863. Sentence P tells us that in November of 1863 an event happened, as sentence R is the only sentence which has a mention of 1863, so sentence P will follow sentence R. Sentence Q is in continuation of sentence R as it tells us that on the occasion that happened in November 1863 a speech was given. RPQ is a sequence only in option B. Hence, option B with sequence RPQS is the correct answer.