Which component of language can alter meaning through addition or removal?

The correct choice is morphemes because they are the smallest units of meaning in a language. Morphemes can be whole words, or they can be parts of words, such as prefixes or suffixes. By adding or removing morphemes, the meaning of words can change significantly. For example, the addition of the suffix "-ed" changes the verb "walk" into "walked," indicating a different tense. Similarly, removing a prefix can change the meaning completely, as seen in transforming “unhappy” to “happy,” which shifts the overall meaning from negative to positive. This ability to manipulate meaning through modification of morphemes illustrates their crucial role in language structure.