Concept:Understanding Samasam (Compound words) and Vigraha Vakyam (Decomposition sentence) in Telugu grammar.Explanation:The term 'వయోవృద్ధుడు' is a compound word (సమాసం). To understand its meaning, we need to break it down into its constituent parts using a 'విగ్రహవాక్యం'.Let's analyze the options:A. 'వయస్సు మరియు వృద్దుడు' means 'age and old person', which doesn't form the intended meaning.B. 'వయసైన వృద్దుడు' means 'aged old person', which is redundant.C. 'వృద్దుని వయస్సు' means 'old person's age', which is the reverse meaning.D. 'వయస్సుచేత వృద్దుడు' means 'old person by age'. This correctly decomposes the compound word and explains its meaning.This type of compound word, where the relationship between the words is indicated by a case ending (విభక్తి ప్రత్యయం), is called 'తృతీయ తత్పురుష సమాసం' (Third Tatpurusha Samasam). Here, the implied case ending is 'చేత' (by/with), connecting 'వయస్సు' (age) and 'వృద్ధుడు' (old person).Answer:D. వయస్సుచేత వృద్దుడు