Which word signals an effect? if since because therefore​

Therefore

Explanation: If, since, and because introduce a cause so therefore would be your only option left

i think the answer is either c or d

im thinking d might make more sense though

sorry if im wrong

in our power to make a world happy - to teach mankind the art of being so - to a character hitherto unknown - and to have, as it were, a new creation intrusted to our hands, are honors that command reflection, and can neither be too highly estimated,