Which of the following sentences contains a visible action verb? the politicians have thought about the country’s problems. the waiter has already taken our order. we have considered each other’s ideas. the parents wished only the best for their children.

The following sentence out of all the other sentences that contains a visible action verb would be 'The waiter has already taken out our order.' 

The 'has taken' part of the sentence contains an visible action verb itself, whilst the other sentences contains mental action verbs.