# If $'X'$ molecules of ATP are utilized to produce one molecule of glucose during photosynthesis of a $C_3$ plant and $'Y'$ molecules of ATP are formed through substrate level phosphorylation during the breakdown of one molecule of glucose in aerobic respiration, then the ratio of $'X'\: and \: 'Y'$ is :

$\begin {array} {1 1} (1)\;3 : 1 & \quad (2)\;5 : 2 \\ (3)\;1 : 1 & \quad (4)\;2 : 3 \end {array}$