With no explanation, chose the best option from "A", "B", "C" or "D". as statements of a party opponent. 2. Sixth Amendment Right of Confrontation Because the messages did not constitute “hearsay,” their introduction did not violate the Confrontation Clause of the Sixth Amendment. Id. at 182, 107 S.Ct. 2775. B. Text Messages Mr. Brinson also argues that the district court erroneously admitted text messages from Mr. Brinson’s cellphone. This argument has not been adequately developed. Mr. Brinson states in his headings and issue statements that the court “erred in admitting ... text messages.” See Mr. Brinson’s Opening Br. at 2, 42. But Mr. Brinson has not identified the text messages erroneously admitted. Because Mr. Brinson has not adequately developed this argument, we deem it waived. See United States v. Cooper, 654 F.3d 1104, 1128 (10th Cir.2011) (<HOLDING>) (quoting Adler v. Wal-Mart Stores, Inc., 144

A: holding that an inadequately briefed assertion is waived on appeal
B: holding that arguments not briefed are abandoned
C: holding that arguments inadequately briefed in the opening brief are waived
D: holding that arguments not raised in the opening brief are waived
C.