A man stands $10 \mathrm{m}$ in front of a large plane mirror. How far must he walk before he is $5 \mathrm{m}$ away from his image?

Man A has a defect of vision due to which he cannot see the nearby objects clearly (though he can see the distant objects clearly). On the other hand, man B has a defect of vision due to which he cannot see the distant objects clearly (though he can see the nearby objects clearly). The defect in man A can be corrected by using spectacles containing lenses C, whereas the defect in man B can be corrected by using spectacles containing lenses D.

Name the defect of vision in man A, and B.

Man A has a defect of vision due to which he cannot see the nearby objects clearly (though he can see the distant objects clearly). On the other hand, man B has a defect of vision due to which he cannot see the distant objects clearly (though he can see the nearby objects clearly). The defect in man A can be corrected by using spectacles containing lenses C, whereas the defect in man B can be corrected by using spectacles containing lenses D.

What type of lenses are C, and D?