The correct option is B welcome
The word 'resist' refers to withstanding the action or effect of something.
Option A, repel refers to driving or forcing something to back away.
Option B, welcome refers to gladly receiving something.
Option C, accept refers to consenting to receive or undertake something offered.
Option D, fight refers to struggling to overcome, eliminate or prevent something.
Thus, according to the meaning, the word 'welcome' is the opposite of the word 'resist'.