The genetical importance of raising haploids in higher plants through tissue culture lies their use in the production of

Question

$\begin {array} {1 1} (1)\;homozygous\: diploids & \quad (2)\;heterozygous\: diploids \\ (3)\;plant\: that\: do\: not\: produce\: flowers & \quad (4)\;hybrid\: plants \end {array}$