Which one of the following statements is not correct with respect to fly ash?

• A. As a partial replacement of cement in the range of 15% — 30%, fly ash reduces the strength in the initial period, but once the Pozzolanic process sets in, higher strength can be obtained
• B. Fly ash as a partial replacement of sand has a beneficial effect on strength even at an early age
• C. All options are correct
• D. A simultaneous replacement of cement and fine aggregates enables the strength at a specified age to be equaled depending upon the water content