Find out which quotation part of the following sentences has an error. He 'gave me' a ticket 'so that' I 'may visit' 'the' book fair

In questions 28-30, each sentence has four underlined words or phrases (A, B, C, or D). Identify the words or phrases that need to be changed to make the sentence correct.

While verbalization is $\frac{the\ most\ common}{\left(A\right)}$ form of language in $\frac{existence}{\left(B\right)}$ humans make use of many $\frac{others\ systems\ and\ technologies }{\left(C\right)}$ $\frac{to\ express }{\left(D\right)}$ their thoughts an: feelings.