What is the rear sight type on the model with the acr muzzle brake device?
CREATE TABLE table_23430 (
    "Colt model no." text,
    "Military designation" text,
    "Barrel Length" text,
    "Barrel" text,
    "Handguard type" text,
    "Buttstock type" text,
    "Pistol grip type" text,
    "Lower receiver type" text,
    "Upper receiver type" text,
    "Rear sight type" text,
    "Front sight type" text,
    "Muzzle device" text,
    "Forward assist?" text,
    "Case deflector?" text,
    "Bayonet lug?" text,
    "Trigger pack" text
)
SELECT "Rear sight type" FROM table_23430 WHERE "Muzzle device" = 'ACR muzzle brake'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: What is the rear sight type on the model with the acr muzzle brake device? ### Input: CREATE TABLE table_23430 (
    "Colt model no." text,
    "Military designation" text,
    "Barrel Length" text,
    "Barrel" text,
    "Handguard type" text,
    "Buttstock type" text,
    "Pistol grip type" text,
    "Lower receiver type" text,
    "Upper receiver type" text,
    "Rear sight type" text,
    "Front sight type" text,
    "Muzzle device" text,
    "Forward assist?" text,
    "Case deflector?" text,
    "Bayonet lug?" text,
    "Trigger pack" text
) ### Response: SELECT "Rear sight type" FROM table_23430 WHERE "Muzzle device" = 'ACR muzzle brake'