Within what timeframe may previously conducted market research be used before the award of a task or delivery order?

a. within 6 months, if the information is still current, accurate and relevant.
b. within 12 months, if the information is still current, accurate and relevant.
c. within 18 months, if the information is still current, accurate and relevant.
d. any timeframe is allowed, as long as the information is still current, accurate and relevant.