Question

what is the meaning of sharp as a tack?
although mr. durand is nearly eighty years old, he is still as sharp as a tack.
able to cut easily
quite old
witty and intelligent

Explanation:

The phrase "sharp as a tack" is an idiom. In English idiomatic usage, it means being very intelligent, quick - witted. In the context of the sentence "Although Mr. Durand is nearly eighty years old, he is still as sharp as a tack", it implies that despite his old age (nearly eighty years old), Mr. Durand has a high level of mental acuity.

Answer:

Witty and intelligent.