Answer:
b. labial
Step-by-step explanation:
labial -
Labial is the surface of the anterior tooth , which faces towards the lips .
The side of tooth , which is just adjacent to the inside of the lip .
This surface is nearest to the lips .
The face of these tooth , i.e. , labial tooth is towards , the lips or cheek , in the human body .
Hence , from the given options the correct answer is b. labial .