What is the key size and IV value for the lightweight symmetric stream cipher Grain?

The lightweight symmetric stream cipher Grain is designed for constrained environments, such as those found in low-power devices. The appropriate key size for Grain is indeed 80 bits, which strikes a balance between security and resource efficiency, particularly suitable for applications where computational overhead and memory usage are minimal. Additionally, Grain utilizes a 64-bit initialization vector (IV), which helps ensure that the same plaintext encrypted with the same key on different occasions yields different ciphertexts, thereby enhancing security through the prevention of certain types of attacks.

This configuration makes Choices A the correct one, as it accurately reflects the established design parameters of the Grain cipher, which is essential for its application in resource-limited environments.