Part a: the sun produces 3.9 ⋅ 1033 ergs of radiant energy per second. how many ergs of radiant energy does the sun produce in 2.45 ⋅ 105 seconds? (5 points) part b: which is the more reasonable measurement of the diameter of a blood cell: 7.4 ⋅ 10−3 mm or 7.4 ⋅ 103 mm? justify your answer

Ascientist wants to use a model to present the results of his detailed scientific investigation. why would a model be useful? a )because the model makes the concepts easier to understand b) because the model is easy to put together and to use c) because the model prevents other scientists from asking questions d) because the model requires the audience to pay full attention to it i don't know what to choose because between a and d a is much more likely than d because it only wants to get the attention of the audience. i'm confuse.