Which of the following best describes a morpheme?

A morpheme is defined as the smallest meaningful unit of language that can carry semantic information. The correct choice highlights that morphemes can exist as independent words (free morphemes) or as parts of words (bound morphemes) that combine with roots or stems to form larger units of meaning. By identifying morphemes as elements that can connect with root words, this option effectively captures the essence of how language is structured and how meaning is conveyed.

For instance, in the word "unhappiness," "un-" is a prefix (bound morpheme), "happy" is a root (free morpheme), and "-ness" is a suffix (bound morpheme). Each component contributes to the overall meaning of the word, illustrating how morphemes work together.

The other options do not accurately represent the definition of a morpheme. A refers to sounds, which are phonemes, not morphemes. B describes larger structures rather than the smallest meaningful units. D incorrectly categorizes morphemes by suggesting they're related to grammatical errors, which does not align with their definition.