I would say 4. To create a hypothesis, you would need some knowledge about what you're studying. This is where prior knowledge could come in handy.
Answer:
The osteoblasts, which should have been building the new bone
Explanation:
Bones are the one of the types of connective tissues and have hard extracellular matrix. Osteoblasts are the cells that serve in formation of extracellular matrix of bones as these cells secrete collagen fibers and inorganic salts present in the matrix of bone. Hence, if a bone is not able to heal after fracture, osteoblast cells should be checked for their activity.
Electricity is caused by moving particles that have either a negative or postivite charge
NASA did not invent the smoke detector.
At the time of this writing, the most recently available statistics pertain to 2010, at which point the World Bank reported that about 37.7 percent of the world's total land area was considered agricultural land, while approximately 10.6 percent was considered arable.
