High-grade tumors typically exhibit increased mitotic activity, presence of necrosis, and poorly differentiated cells, making 'All of the above' the correct answer.

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer, accounting for approximately 85% of cases.

Tumors are primarily classified as benign or malignant based on their histological appearance, which reflects their cellular characteristics and behavior.

Immunohistochemistry is the primary method used for the histopathological diagnosis of tumors, allowing for the identification of specific antigens in tissue sections.

Tumor grading is significant as it predicts the tumor's behavior and prognosis based on the degree of differentiation and histological features.

Carcinoma in situ is characterized by abnormal cells that are confined to the epithelium and have not invaded surrounding tissues.

Benign tumors typically exhibit capsule formation, which helps to distinguish them from malignant tumors that often invade surrounding tissues.

Direct contact spread is not a common route of metastasis for solid tumors; instead, they typically spread via hematogenous, lymphatic, or transcoelomic routes.

Osteosarcoma is classified as a sarcoma, which is a malignant tumor arising from connective tissues, while the others are carcinomas.

AFP (Alpha-fetoprotein) is a tumor marker commonly associated with hepatocellular carcinoma.