Biology

Pedology is the scientific study of soils, including their formation, classification, and mapping. Therefore, the correct answer is 'Soils'.

The human body typically has around 639 skeletal muscles. This is the most commonly accepted number in anatomy, making option A correct.

The lungs are located in the thoracic cavity, which is the part of the body cavity enclosed by the ribs and diaphragm. The other options are incorrect or misspelled.

Each human hand contains 27 bones: 8 carpal bones in the wrist, 5 metacarpal bones in the palm, and 14 phalanges in the fingers. Therefore, option C is correct.

The innermost part of the eye is the retina, which contains photoreceptor cells that detect light and send signals to the brain. The pupil is the opening that allows light in, and the iris is the colored part controlling the pupil size.

The adult human skeleton typically consists of 206 bones. This is a well-established fact in human anatomy.

The cytoplasm is the living material within the cell where organelles are suspended and carry out their functions. Chlorophyll is a pigment, the cell wall is a rigid outer layer, and 'None of these' is incorrect.

The number of muscles in the human body varies depending on the counting method and source, but most reliable sources agree there are over 600 muscles. Estimates commonly range from about 600 to 840 muscles, with around 639 often cited as a standard count for skeletal muscles. The exact number can vary due to anatomical variations and how muscles are classified. Therefore, option A (639) is the most accurate choice among the given options.

The longest cell in the human body is the nerve cell (neuron), as some neurons can extend over a meter in length, such as those running from the spinal cord to the toes. Other cells like liver or kidney cells are much smaller in comparison.

Growth hormone primarily acts on most somatic cells to stimulate growth, cell reproduction, and regeneration. While it affects various tissues, its main regulatory function is on somatic cells rather than nerve or liver cells specifically.