Read the passage and answer the question: There are no unemployed, no slackers, in an ant community. Whilst the nurse ants are looking after the young, sentinel ants are mounting guard to give warning of the approach of an enemy. Meanwhile other ants will be hard at work, collecting food, repairing the nest, or milking the ants' cows. Yes, ants keep cows, and some ants even make stalls of leaves and silk in which to house their cows, and covered galleries along which the milkers can go to and fro from the stalls in safety. — The word 'slacker' means