a) 33-35 cm from bottom of the mould
b) 33-35 mm from top of the mould
c) 33-35 cm from top of the mould
d) 33-35 mm from bottom of the mould

Answer: b
Explanation: The best procedure has been clearly mentioned in IS 4031 Part 4. According to the code, 33-35mm depth of penetration is ideal.