OE

The gist of the first sentence seems to be that studying viruses is important because its findings may affect other areas of medicine - the missing word probably means something like implications. Proscriptions is probably too specific; it means prohibitions, and while it is not inconceivable that a medical study might lead to some prohibitions or restrictions, this particular passage mentions nothing of the kind. You can eliminate exigencies (a state that demands prompt remedy or action or the need intrinsic to a situation) for the same reason. The best answer is ramifications (outgrowths or consequences).



The second half of the passage deals with the potentially harmful consequences of otherwise innocuous viruses, which, we are told, have been linked to certain forms of cancer. It would be unusual to use the word truncate in the context of a disease, but the context makes it a poor choice regardless; it means to shorten, which, when speaking of cancer, would be a good thing. To attenuate means to weaken or reduce in force - again, a desirable effect in the context of a disease. This leaves you with precipitate, which means to hasten the occurrence of.