What was the first year Corvette was offered with the ZR1 option?

In 1970 a special ZR1 option package offered only on LT-1 Cars included Muncie M22 Transmission, racing suspension, brakes, stabilizer bars, and other high performance components.

Side notes: Production volume in 1970 was down nearly 60% with 17,316 units compared to 1969. Rare options for the model year included: ZR1 special engine package (25), shoulder belts in convertibles (475), LT-1 engine (1,287).

The correct answer: 1970