Which is correct? a. there are 0.35 hectoliters in 35 deciliters. b. there are 7.62 centiliters in 762 liters. c. there are 6.8 kiloliters in 68 hectoliters. d. there are 0.75 deciliters in 7.5 liters.

Below is the conversion table for letter A to D:
1 deciliter = 0.001 hectoliters
1 liter = 100 centiliters
1 kilolieter = 10 hectoliter
1 liter = 10 deciliter

The correct one would be letter C - There are 6.8 kiloliters in 68 hectoliters. Since 1 kiloliters (kl) is equal to 10 hectoliters (hl), 6.8 kl times 10 is equal to 68 hl.