Which of the following statements is true of adding adjacent borders to a table using CSS$?$

a$.$ The border style with the highest priority is used if the two borders have the same width but different styles.

b$.$ A border style of none is overridden by the same border style.

c$.$ The color of the element in the table with the lower priority takes precedence if the borders differ only in color.

d$.$ A narrow border takes priority over a wider border if neither is hidden.