Answer :
Semantic processing is the aspect of language processing that Kemper (1984) found to be most commonly affected in individuals with dementia, as it involves the meaning and comprehension of words. So, option (a) is correct.
According to Kemper (1984), the aspect of language processing most commonly affected in individuals with dementia is semantic processing. This is consistent with findings by Craik and Tulving (1975), who discovered that semantic encoding involves a deeper level of processing and leads to better memory recall compared to visual or acoustic encoding.
Accordingly, the semantic aspect of language, which is related to the meaning and comprehension of words, is more likely to be compromised in patients with dementia.