In the sentence "In spoken languages units of sound and meaning are combined sequentially.", the word "sequentially" can be replaced by_____.

A．It is to represent letters of the alphabet.
B．Finger spelling serves as a way to differ from spoken language.
C．Finger spelling means you can spell the word by fingers.
D．It is a convenient way to communicate with the other people.

A．Linguists have found that sign languages and spoken languages differ from each other in many features.
B．Like spoken languages, which use units of form to produce words, sign languages use units of sounds.
C．Separately, b, e, and t have a meaning and together they form the word bet.
D．Spoken languages contain units of form that by themselves hold no meaning, but when combined create a word.