Which of the following are considered sex cells?

Gametes are indeed the cells responsible for sexual reproduction and are classified as sex cells. In humans, they include sperm and eggs, which are produced in the male and female reproductive systems, respectively. The primary function of gametes is to fuse during fertilization to form a zygote, initiating the development of a new individual.

The other options refer to different types of cells with specific roles in the body. Fibroblasts are important for producing extracellular matrix and collagen, contributing to the structural framework of tissues. Myocytes, or muscle cells, are specialized for contraction and movement. Chondrocytes are the cells found in cartilage, playing a crucial role in its maintenance and repair. Each of these cell types serves specialized functions unrelated to reproduction, highlighting the unique role of gametes as sex cells.