The type of cells that contain 23 single chromosomes are gametes, also known as sex cells. These are sperm cells in males and egg cells in females.

Here's why:

* Diploid cells: Most cells in our body are diploid, meaning they have two sets of chromosomes (46 total in humans).

* Haploid cells: Gametes are haploid, meaning they have only one set of chromosomes (23 total in humans).

* Fertilization: When a sperm cell fertilizes an egg cell, their chromosomes combine to form a diploid zygote with 46 chromosomes.

So, the 23 single chromosomes in gametes ensure that the offspring inherits half of its genetic material from the mother and half from the father.