This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
First sound by child is: 
Select and explain. 
A. Sibilant, B. Bilabial, C. Fricative, D. Monolabial
B: Bilabial
Answer: B: Bilabial 
Explanation: Most children are able to produce the bilabial sounds (made with the lips) of “b, p, m, w” ﬁrst, since these are sounds visible on the lips. 
They may also produce sounds (linguo-alveolar) such as “d, n, t” early on as well.
These sounds are called linguo-alveolar, since they are produced with the tongue behind the teeth against the alveolar ridge in the mouth.