Brain Teasers and Puzzles

A box for your workings out:

Hint: The first word is I.

Answer: I think, therefore I am.

A represents a, b, c, d and e. B represents f, g, h, i and j. C represents k, l, m, n and o. D represents p, q, r, s and t. E represents u, v, w, x, y and z. F represents z.