Explanation:

- These discount coupons are relevant for a specific duration from the date they are issued.

- Option 1: Attested

- "Attested" means verified or certified. It doesn’t fit the context of describing the time-based usefulness of coupons.

- Option 2: Tested

- "Tested" refers to something being tried or examined, which doesn't apply directly to the duration or validity of coupons.

- Option 3: Valid

- "Valid" means legally acceptable or officially acceptable for a specified period. It is the appropriate word to describe the time limit attached to the coupons.

- Correct Answer: Valid

- Option 4: Solid

- "Solid" implies firmness or strength, and it doesn't relate to the concept of time-bound effectiveness.