9) Antonio was born on the $1^{\circ}$ March of a year that had 53 Saturdays and 53 Sundays. On which day of the week was he born?

(A) Monday (B) Wednesday $(\mathbf{C})$ Friday

(D) on a different day from the above (E) it cannot be determined with certainty.
9) The answer is (B).

Indeed, the year Antonio was born was a leap year, as a non-leap year has 52 weeks plus one day, and therefore has only one day of the week that repeats 53 times. In a leap year, the days that repeat 53 times are necessarily the first and second day of the year. So January 1st was a Saturday, and counting that January had 31 days and February had 29, March 1st was a Wednesday.