19.
Your Answer is
Correct Answer is C
Explanation
When paralleling two sentences with and, repeated verbs can be omitted, for example, he can play football and I (can play) tennis. And, when the following sentence is short enough, there is no need to add a comma in front of and, item C is correct.
A item: for as "because" is a conjunction, and a sentence must be added after it.
Item B: Add a sentence after so that.
Item D: There is no turning relationship before and after.