以optochin disk對某α-溶血鏈球菌作感受性試驗，形成抑制圈，可配合下列何種試驗以確認其是否為Streptococcus pneumoniae？
growth on brain heart infusion agar with 6.5% NaCl
bile esculin agar
bile solubility test
β-D-glucuronidase test
