Select the incorrect statements :
(a) alimentary canal begins with an anterior cavity called buccal cavity.
(b) tooth is embedded in a socket of mandible bone only.
(c) human shows strict diphyodont type of dentition.
(d) oesophagus and the trachea open into the pharynx.

Options

A. a,b,c &d
B. a,b&c
C. a,c&d
D. a,b&d

Answer

To solve the question of selecting the incorrect statements regarding the alimentary canal and dentition, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement (a): "Alimentary canal begins with an anterior cavity called buccal cavity."**
- The alimentary canal does indeed begin with the mouth, which includes the buccal cavity. However, the term "buccal cavity" is often used interchangeably with "oral cavity." The statement is misleading because it implies that the alimentary canal starts specifically with the buccal cavity, which is not entirely accurate. Thus, this statement is **incorrect**.

2. **Statement (b): "Tooth is embedded in a socket of mandible bone only."**
- Teeth are not only embedded in the mandible (lower jaw) but also in the maxilla (upper jaw). The sockets that hold the teeth are part of the alveolar process, which is present in both the mandible and maxilla. Therefore, this statement is also **incorrect**.

3. **Statement (c): "Humans show strict diphyodont type of dentition."**
- Humans are classified as diphyodonts because they develop two sets of teeth: primary (deciduous) and permanent teeth. However, the term "strict diphyodont" may be misleading as humans do not have a perfect two-set system due to the presence of wisdom teeth, which can be considered as a third set for some individuals. Thus, this statement is **incorrect**.

4. **Statement (d): "Oesophagus and the trachea open into the pharynx."**
- This statement is correct. The pharynx serves as a passageway for both the digestive system (leading to the esophagus) and the respiratory system (leading to the trachea). Therefore, this statement is **correct**.

### Conclusion:
The incorrect statements are:
- (a) Alimentary canal begins with an anterior cavity called buccal cavity.
- (b) Tooth is embedded in a socket of mandible bone only.
- (c) Humans show strict diphyodont type of dentition.

Thus, the answer is that the incorrect statements are **A, B, and C**.