已知数列\(\{a _{n} \}\)满足\(a_{1}= \dfrac {1}{2}\)，\(a_{n+1}= \dfrac {2}{1+a_{n}}\)，则\((\:\:\:\:)\)
A. \(a _{2021} < a _{2019} < a _{2022} < a _{2020}\)
B. \(a _{2021} < a _{2019} < a _{2020} < a _{2022}\) C. \(a _{2019} < a _{2021} < a _{2022} < a _{2020}\) D. \(a _{2019} < a _{2021} < a _{2020} < a _{2022}\)
