veekay wrote:Not sure why this is chosen over others...

Good one!

Please anybody help needed!

okay here is my understand:
galileo must be used in the first part as a subject because "he" needs an antecedent; therefore, d and e are out.
next phase is to choose the best verb tense.
X didnt make Y, but on hearing that Y had been made, X built his/her own Y.
the first part says that X didnt make Y, but he made it after hearing that Y had been made. Had been is used to emphasize that Y was made sometimes in the past before X make it and still in progress, later he made his own. A is right. B is wrong and will catch most of he students attention as a right option. C is wrong, did must be used.

I am sorry i worst in explaining things.. hope this helps..Cheers

You need a pronoun to refer to in the last part of the sentence. Hence "he" is required. Eliminate B and D.

Eliminate E because it just sounds very wrong. "but when he heard,1609, "

C distorts the meaning to a point where it does not make any logical sense. "Galileo, even though he had not invented the telescope, on hearing, in 1609,"

Another reason for A - Galileo not inventing the telescope is a fact. Hence it should be stated in simple present tense.

Hope that helps.