SENTENCE shows the USE of conjunctions, indicating that they are meaningfully related to each other.Out of the given sentences, only sentence T introduces the TOPIC i.e. 'Anorexia' while others give more information about it.So, there are two sentences which are starting with sentence P. Let us take a look at both of them.Sentence R explains about someone who is suffering from the disorder.Out of the given options, option 3 reflects this ORDER i.e. PR.Therefore, the correct answer is option 3.