Which of the following endocrine glands is not found in pair in humans?

Which of the following is an example of an Endocrine gland in the human body?

Which of the following glands in human body acts both as an endocrine gland as well as an exocrine gland?

Among the following options, which is the smallest endocrine gland in the human body?

In the human body, which of the following is ductless gland?

Which gland in the human body acts as both an endocrine and an exocrine gland?