With no explanation, chose the best option from "A", "B", "C" or "D". applicable to the fourth element of a prima facie case of discrimination in the context of a RIF are not fully defined. See Beaird, 145 F.3d at 1166. Although “evidence that an employer fired qualified older employees but retained younger ones in similar positions is sufficient to create a rebuttable presumption of discriminatory intent,” Branson v. Price River Coal Co., 853 F.2d 768, 771 (10th Cir.1988), questions such as “whether a single younger employee retained in a similar position is sufficient to establish the fourth element, or how similar a position must be in order to be relevant under Branson,” remain unanswered. Beaird, 145 F.3d at 1166. See Stone v. Autoliv ASP, Inc., 210 F.3d 1132, 1137-38 (10th Cir.2000); Krause v. Dresser Indus. Inc., 910 F.2d 674, 677 (10th Cir.1990) (<HOLDING>). “To make a comparison demonstrating

A: holding that when a 56year old employee was replaced by a 40year old employee this qualified as someone substantially younger for the purposes of establishing a prima facie case
B: holding that proof that an employer fired an employee three months after the employee filed a charge of discrimination sufficed to state a prima facie case of causation
C: holding in a rif context that the fourth prima facie element is satisfied if the plaintiff can show that he was discharged while the company retained someone younger
D: holding prima facie case established where employer fired fiftytwo year old accountant pursuant to rif but retained one younger employee in similar position
D.