What basic modifications have been made in evolutionary theory since darwin's time?

Knowledge of genetics did not yet exist in Darwin's time, so genetic theory has since been used to explain natural selection. In addition, Darwin believed that evolution progressed at a slow, steady rate. However, that idea has been replaced by the punctuated equilibrium model, in which major changes in brief spurts.

(Mark this as the brainliest answer if this helps!)

the answer is "a.) well–developed vascular system."

explanation: