Read the passage. (1) Does cell phone use lead to harmful effects from radiation? (2) Many Americans would love to know the answer, since cell phone use is at an all-time high. (3) Cell phone users abound, most are not well informed about the potential hazards associated with cell phones. (4) Therefore, cell phones should come labeled with information regarding the dangers of using them. Which transition would be best to use at the beginning of sentence 3? Most importantly In addition Although Therefore

The transition that would be best to use at the beginning of sentence 3 is Although

Explanation:

The best way to make the transition from sentence 2 to sentence 3 is "Many Americans would love to know the answer, since cell phone use is at an all-time high. ALthough Cell phone users abound, most are not well informed about the potential hazards associated with cell phones. "Although" is used to present contrast and we can see that we have a big quantity of American users who love their devices and would love to know the information but there are only a few who have that are actually aware of that information.

Although cell phone users abound, most are not well informed about the potential hazards associated with cell phones.

Explanation:

In the passage, it can be a transition in sentence 3 because it is presented a situation where people are not well informed about potential hazard which cell phone can make. The transition although explains that there is a fact about many cell phone users, but there are not many pieces of information about the hazard of cell phones.