Which of the following statements is/are correct?1. Isochrones are curves of equal pore water pressure2. Isochrones depict the variation of the pore water pressure along with the depth of the soil sample3. Isochrones vary with time

• A. 1 only
• B. 2 and 3 only
• C. 1 and 2 only
• D. 1, 2 and 3