已知数列\(\{a _{n} \}\)由首项\(a _{1} =a\)及递推关系\(a_{n+1}= \dfrac {3a_{n}-1}{a_{n}+1}\)确定．若\(\{a _{n} \}\)为有穷数列，则称\(a\)为“坏数”\(.\)将所有“坏数”从小到大排成数列\(\{a _{n} \}\)，若\(b _{2019} < a _{1} < b _{2020}\)，则\((\:\:\:\:)\)
A. \(-1 < a _{2020} < 0\)
B. \(0 < a_{2020} < \dfrac {1}{3}\) C. \(a _{2020} > 3\) D. \(1 < a _{2021} < 3\)
