C. The number of covalent bonds is equal to the number of unpaired valence electrons. For example, nitrogen and phosphorous both have 3 unpaired valence electrons thus forming 3 covalent bonds.
The correct answer is carcinoma. Mammary duct ectasia, papilloma and fibroadenoma are benign conditions of the breast. <span>Breast carcinoma is malign cancer that develops from breast tissue. Breast cancer is the<span> most common cancer among women</span> which can be the result of genetic or lifestyle factors. Invasive ductal carcinoma (IDC) is the most common type of breast cancer<span>.</span></span>
Explanation:
The circulatory and respiratory systems work together to circulate blood and oxygen throughout the body. Air moves in and out of the lungs through the trachea, bronchi, and bronchioles. Blood moves in and out of the lungs through the pulmonary arteries and veins that connect to the heart.
Answer:
xylem cell and phloem cell
