The sentence that is more clear to the readers is -Neil Armstrong, before he became the first man to walk on the moon, was an aerospace engineer, naval aviator, test pilot, and professor – that’s quite a list of accomplishments!
Explanation:
Considering the other options
1)Neil Armstrong before he became the first man – to walk on the moon – was an <u>Aerospace Engineer Naval Aviator</u> Test Pilot and Professor, that’s quite a list of accomplishments!-This statement is grammatically incorrect because commas are missing between two words like Aerospace engineer naval aviator
2)Neil Armstrong before, he became the first man to walk on the moon, was an Aerospace Engineer. Naval Aviator Test Pilot and Professor, that’s quite a list of accomplishments-This statement is also grammatically incorrect because Full Stop(.)is used instead commas(,) needs to be used.
3)Neil Armstrong before he, – became the first man to walk on the moon, was an Aerospace Engineer. Naval Aviator Test Pilot and Professor, that’s quite a list – of accomplishments!- This statement is also grammatically incorrect because - should not be used ,in appropriate use of commas.