Final answer:
The maximum safe length of lancets used for heel puncture is 2.4 mm.
Step-by-step explanation:
The maximum safe length of lancets used for heel puncture is 2.4 mm. The depth of the puncture is directly related to the length of the lancet, as the heel is a sensitive area and requires a controlled depth.
Using a lancet that is too long can lead to unnecessary pain, injury, and increased risk of infection. On the other hand, using a lancet that is too short may not be able to effectively collect an adequate blood sample.
In conclusion, the correct option is 2.4 mm, which ensures a safe and efficient heel puncture for blood collection.