With no explanation, chose the best option from "A", "B", "C" or "D". days after serving it, or (B) if the pleading is one to which a responsive pleading is required, 21 days after service of a responsive pleading or 21 days after service of a motion under Rule 12(b), (e), or (f), whichever is earlier.” Fed. R. Civ. P. 15(a)(1). “In all other cases, a party may amend its pleading only with the opposing party’s written consent or the court’s leave,” which “[t]he court should freely give [ ] when justice so requires.” Fed. R. Civ. P. 15(a)(2); see also Foman v. Davis, 371 U.S. 178, 182, 83 S.Ct. 227, 9 L.Ed.2d 222 (1962) (“Rule 15(a) declares that leave to amend ‘shall be freely given when justice so requires.’ ”); Willoughby v. Potomac Elec. Power Co., 100 F.3d 999, 1003 (D.C.Cir.1996), cert. denied, 520 U.S. 1197, 117 S.Ct. 1553, 137 L.Ed.2d 701 (1997) (<HOLDING>); Norris v. Salazar, 885 F.Supp.2d 402, 414

A: holding that leave shall be freely given to amend a complaint is a mandate  to be heeded
B: holding that leave to amend should be freely given unless there is a good reason such as futility to the contrary
C: holding leave to amend should be freely granted absent a showing of undue delay bad faith undue prejudice or futility
D: holding that futility is among the reasons for denying leave to amend a complaint
B.