This Question Refers to Flight Pioneers

Read the sentence below from paragraph 7
“Although they never reached the pinnacle of success they had hoped for , their pioneering work was INSTRUMENTAL in giving us the beginning of man’s ventures into flight”
Which word means the same as INSTRUMENTAL as it is used in this way?
A. contributory
b. cooperative
c. impressive
d.suitable

Bot GPT 3.5 Bot GPT 3.5 answered

A. contributory