**Core Concept**
The question relates to the concept of the force required for bodily movement of a tooth, which involves moving the tooth in its entirety without any tipping or rotation. This is a key principle in orthodontics and dental anatomy, where the force applied must be sufficient to move the tooth through the surrounding bone and periodontal ligament.

**Why the Correct Answer is Right**
The force required for bodily movement of a tooth is directly related to the resistance offered by the periodontal ligament and the surrounding bone. The periodontal ligament provides a significant amount of resistance to tooth movement due to its fibrous structure and the presence of Sharpey's fibers, which insert into the bone. To overcome this resistance, a sufficient force must be applied to the tooth to cause it to move through the periodontal ligament and into the surrounding bone. The correct answer represents the minimum force required to achieve this movement.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it is not a valid unit of measurement for force.
**Option B:** Incorrect because it is too low and would not be sufficient to overcome the resistance offered by the periodontal ligament and surrounding bone.
**Option C:** Incorrect because it is too high and would likely cause more than just bodily movement of the tooth, potentially leading to damage to the surrounding bone and periodontal ligament.

**Clinical Pearl / High-Yield Fact**
A common mnemonic to remember the forces required for different types of tooth movement is "3-5-7": 3 grams for tipping movement, 5 grams for bodily movement, and 7 grams for rotational movement.

**Correct Answer: D. 1500 N (Newtons)**