Although: conjunctions indicate turning points.
Because: conjunctions indicate reasons.
Commonly used in spoken language, because in written language, "because" can be combined with "so, so" and "because" cannot be used together. Because it can be used in the last sentence, "because" can't ". Because of the different fonts, China's calligraphy can be divided into "static" and "dynamic" in overall style, so the first blank is filled with the cause and effect of two sentences.
(2) The "but" table has turned.
"So" table results.
The overall style of China's calligraphy can be divided into two forms: static and dynamic, but the static and dynamic in calligraphy creation are relative and compatible, and the binary sentence of "China Calligraphy" is a turning point, so the second one is full of "buts".
(3) "therefore" reasons.
"But" the table turned.
"Static and dynamic in calligraphy creation are relative and compatible, and the handling of the relationship between static and dynamic in pen modeling can better reflect the calligrapher's spiritual tolerance and artistic skill." The second sentence is causality.
So choose: a.