The answer to the question '<span>In a series of undisturbed rock layers where shale lies between sandstone below and limestone above, the __." would be limestone is youngest. Out of all the rock layers, the limestone is dated to be the youngest of all.</span>
First satellite was Sputnik and it was a race then to send satellites!! Everyone starts experimenting how to launch.
first try was on a dog , Laika !! It was send to space as it is long after sputnik is placed in orbit !!
Now you know everyone knows rocket science and the most active are ISRO (India) and NASA (USA) !!
I think it is B, because the sun’s size is pretty average