A 4-isotropic element broadside array separated by a λ/2 distance has nulls occurring at ____________

• A. \(cos^{-1} (±\frac{n}{2}) \)
• B. \(cos^{-1} (±\frac{4n}{2}) \)
• C. \(sin^{-1} (±\frac{n}{2}) \)
• D. \(sin^{-1} (±\frac{n}{4}) \)