Correct answer: −1
The expression 49^λ + 16ⁿ + λ must be evaluated under modulo 64 conditions. For n being a natural number, 16ⁿ is always divisible by 64 when n ≥ 2, thus the focus is on the terms 49^λ and λ. The term 49^λ can be simplified as (49 mod 64)^λ, which is 49, and we find that for λ = -1, the expression becomes 1 + 0, satisfying the divisibility condition. Hence, the greatest negative value of λ that maintains this divisibility is -1.