Phép tính sau đúng hay sai?

$\dfrac{1}{9} + \dfrac{4}{9} = \dfrac{{1 + 4}}{{9 + 9}} = \dfrac{5}{{18}}$

A. \(\dfrac{4}{5}\)

B. \(\dfrac{5}{4}\)

C. \(\dfrac{4}{9}\)

D. \(\dfrac{5}{9}\)

A. \(\dfrac{{12}}{{16}}\)

B. \(\dfrac{{12}}{{18}}\)

C. \(\dfrac{2}{3}\)

D. \(\dfrac{3}{4}\)

A. \(\dfrac{5}{6}\,\,;\,\,\,\dfrac{2}{3}\,\,;\,\,\,\dfrac{8}{7}\,\,;\,\,\,\dfrac{1}{2}\)

B. \(\,\,\dfrac{8}{7}\,\,;\,\,\,\dfrac{5}{6}\,\,;\,\,\,\dfrac{2}{3}\,\,;\,\,\,\dfrac{1}{2}\)   

C. \(\,\,\dfrac{8}{7}\,\,;\,\,\,\dfrac{2}{3}\,\,;\,\,\,\dfrac{5}{6}\,\,;\,\,\,\dfrac{1}{2}\)

D. \(\,\,\dfrac{8}{7}\,\,;\,\,\,\dfrac{5}{6}\,\,;\,\,\,\dfrac{1}{2}\,\,;\,\,\,\dfrac{2}{3}\,\,\)