What do mast cells secrete?

Which of the following statement$(s)$ is/are correct?
$(i)$ Loose connective tissue contains fibroblasts,macrophages and mast cells.
$(ii)$ Adipose tissue is a type of dense connective tissue located mainly beneath the skin.
$(iii)$ Tendons and ligaments are examples of dense connective tissue.
$(iv)$ Cartilage and bones are types of specialized hard connective tissue.

Where would you find mast cells?

Bone is distinguished from cartilage by the presence of

What are the intervertebral discs made of?

Tendons and ligaments are specialized types of which tissue?