Which one of the following is not considered a major function of bones in the human skeletal system?

Introduction / Context:
Bones are more than simple rigid structures. The skeletal system performs several important functions in the human body, including support, protection, movement, and blood cell formation. General science and biology questions often ask which functions are correctly attributed to bones and which are not. This helps students separate the role of bones from that of glands and other organs.

Given Data / Assumptions:
- The question asks which listed item is not a function of bones.
- Options include protection of organs, hormone secretion for calcium regulation, muscle attachment, and production of blood corpuscles.
- We assume standard school level teaching about skeletal functions.
- The focus is on the main, classical functions of bones rather than advanced endocrine details.

Concept / Approach:
The major functions of bones include providing structural support, protecting vital organs, serving as levers for movement with muscles, storing minerals like calcium and phosphorus, and housing bone marrow where blood cells are produced. These are widely taught in school textbooks. Regulation of calcium in blood involves hormones such as parathyroid hormone and calcitonin, which are secreted by glands like the parathyroid and thyroid. While bones store and release calcium under the influence of these hormones, bones themselves are not usually described at this level as secreting the main hormones that regulate blood calcium. Therefore, the statement about secretion of hormones for calcium regulation is not considered a primary function of bones in basic general science.

Step-by-Step Solution:
Step 1: List the well known functions of bones: support, protection, movement with muscles, mineral storage, and blood cell formation. Step 2: Recognise that protecting organs like the brain and heart is a clear function of skull and rib cage. Step 3: Recall that muscles attach to bones, allowing movement at joints when muscles contract. Step 4: Remember that bone marrow inside many bones produces red and white blood cells. Step 5: Notice that secretion of hormones for calcium regulation is primarily the role of endocrine glands rather than a direct function attributed to bones in school level teaching.

Verification / Alternative check:
Biology textbooks list the functions of the skeleton and often include diagrams showing protection of the brain by the skull, lungs and heart by the rib cage, and bone marrow producing blood cells. They describe hormonal control of calcium as a function of glands, with bones responding to these hormonal signals by releasing or storing minerals. Bones therefore participate in calcium balance but are not introduced in basic courses as hormone secreting organs. This supports the view that the listed hormone secretion function is the odd one out in this question.

Why Other Options Are Wrong:
- Protection of vital organs is a well established function of bones; for example, the skull and rib cage protect the brain and thoracic organs.
- Providing a place for muscle attachment is a central role of bones, enabling movement when muscles pull on them.
- Production of blood corpuscles, especially red blood cells and many white blood cells, occurs in the bone marrow within certain bones.

Common Pitfalls:
Some learners may overgeneralise and think that since bones are involved in calcium storage, they must also secrete the hormones that regulate calcium level, which is not what basic curricula teach. Others may misread the question and choose a true function by mistake. A careful reading and a quick recall of the list of skeletal functions can prevent such errors. It is helpful to memorise the classic functions: support, protection, movement, blood cell formation, and mineral storage, and then treat unfamiliar or gland focused functions with caution in such questions.

Final Answer:
The option that is not considered a major function of bones is Secretion of hormones for calcium regulation in blood and bones.