Bonjour Archana,

It is great to see that you are taking such an interest in finding out why some of your answers aren't/are correct. As Jim kindly mentioned, it may be easier to do a bit more research (especially when it cones to verbs/words) on your end. Jim's references are excellent!  ;-)

I have explained below why some of your suggestions do not fit:

1. "récompensant" is not used in this way. "A reward / To reward" ( = a compensation) can be translated as "une récompense / Récompenser". However, it isn't working in this context (as it means "satisfying" -> gratifiant) 

2. "ausculter" = to examine (a body) vs "diagnostiquer" = to diagnose (an illness)

3. "pour sept ans" refers to a future duration and therefore doesn't work here - See lesson link here: Expressing for + [duration] in French with either pendant/durant/depuis/pour (French Prepositions of Time)

I hope this is helpful!

Bonne journée !