Final answer:
The correct statement about word formation is that a morpheme is the smallest unit of meaning. Compound words are formed from two parts, and suffixes come after the base of the word. Assimilation changes prefixes like 'ad-' in certain combinations.
Step-by-step explanation:
In relation to word formation, the correct statement is that a morpheme is defined as the smallest linguistic unit that has meaning. Compound words are typically formed by combining two lexical items, not three. The word postman is not an example of a word using the prefix post to represent after, rather, it is a compound word formed from 'post' (related to mail) and 'man'.
The suffix is not the part of a word that comes before the base or stem; it comes after the base or stem.
For example, if we take the stem 'gallery' and add the suffix 'ies' to form 'galleries', the letters that spell [ē] are marked in the resulting word. Similarly, when combining 'hurry' with 'ies', we get 'hurries', where 'ie' marks the [ē] sound.
Additionally, when dealing with prefixes and assimilation, the prefix 'ad-' changes form when added to stems starting with certain letters. For example, ad- can become 'ar-' when added to a stem starting with an 'r', as seen in the assimilation process where 'ad-' + 'rive' becomes 'arrive'.