The sketch shows a column with a pin at the base and rollers at the top. It is subjected to an axial force $P$ and a moment $M$ at mid-height. The reaction(s) at R is/are

1. a vertical force equal to $P$
2. a vertical force equal to $P/2$
3. a vertical force equal to $P$ an a horizontal force equal to $M/h$
4. a vertical force equal to $P/2$ and a horizontal force equal to $M/h$