the interval shown here represents a

weak acid
strong acid
weak base
strong base

The pH scale was given by Sorensen to quanitatively define strength of an acid and base

the pH scale extends from 0 to 14

For acids

The pH should be less than 7 [always]

For base

The pH should be more than 7 [always]

The pH seven is of neutral solution

pH = -log[H+]

Thus lower the pH higher the concentration of hydronium ion or protons produced by an acid

thus for the given pH scale interval [0-3] it represents strong acid [Which will give high concentration of protons on dissociation]