Question

The Primary dentition in humans differs from permanent dentition in not having one of the following types of teeth.
A) Canine
B) Premolars
C) Molars
D) Incisors

Answer 1

There are four classes of teeth; incisors, canines, premolars, and molars. The primary dentition consists of 20 teeth often these teeth are referred to as deciduous teeth.

Complete answer:

The primary dentition consists of 20 teeth. These teeth will be exfoliated as the permanent teeth erupt. In each arch of the mouth, there are two central incisors, two lateral incisors, two canines, and four molars.
The permanent dentition consists of 32 teeth. There are 16 teeth in the Maxilla and 16 in the mandible. In each arch, there are two central incisors, two lateral incisors, two canines, four premolars, and six molars.
We can see there are no premolars in primary dentition (baby teeth). These are found only in permanent dentition (adult teeth.)
The primary dentition is composed of 20 teeth, 10 within each arc. There are five in each quadrant, composed of two incisors (Central and lateral) a canine, and two molars. These teeth are referred to as letter’s $A,{\text{ }}B,{\text{ }}C,{\text{ }}D{\text{ }}and{\text{ }}E$
the primary teeth begin to erupt at 6 months of age.
Whereas the permanent dentition is composed of 16 teeth in each arch. There are 8 teeth in each quadrant, composed of two incisors, a canine, two premolars, and three molars. These teeth are referred to as numbers, $1$(central incisor) to $8$ (${3^{rd}}$ molar or wisdom tooth.)
Primary teeth duration is from $6$ months to ${5^{\frac{1}{2}}}$ year and the duration starts for permanent is ${6^{\frac{1}{2}}}$ onwards.

So the correct answer is B).

Note: The human dentition is usually categorized as being primary and permanent dentition.
The permanent dentition is the second set of teeth and also known as adult teeth.
Primary teeth are similar to smaller in size. When compared to permanent teeth. Primate space is absent in primary teeth.