在华北地区某大城市的控制性详细规划中，下列哪个地块的指标比较合理（  ）<table border="0" cellspacing="1" cellpadding="0" _dj="MsoNormalTable"><tbody><tr><td valign="top" width="55"></td><td valign="top" width="79">用地性质 </td><td valign="top" width="78">用地面积 </td><td valign="top" width="67">容积率 </td><td valign="top" width="78">建筑密度 </td><td valign="top" width="67">绿地率 </td><td valign="top" width="79">建筑高度 </td></tr><tr><td valign="top" width="55">① </td><td valign="top" width="79">R21 </td><td valign="top" width="78">83200m2 </td><td valign="top" width="67">-2．1 </td><td valign="top" width="78">36% </td><td valign="top" width="67">30% </td><td valign="top" width="79">45m </td></tr><tr><td valign="top" width="55">② </td><td valign="top" width="79">R11 </td><td valign="top" width="78">37400m2 </td><td valign="top" width="67">1．1 </td><td valign="top" width="78">25% </td><td valign="top" width="67">40% </td><td valign="top" width="79">10m </td></tr><tr><td valign="top" width="55">③ </td><td valign="top" width="79">C2 </td><td valign="top" width="78">15000m2 </td><td valign="top" width="67">4．0 </td><td valign="top" width="78">45% </td><td valign="top" width="67">25% </td><td valign="top" width="79">100m </td></tr><tr><td valign="top" width="55">④ </td><td valign="top" width="79">R／C </td><td valign="top" width="78">54900m2 </td><td valign="top" width="67">6．0 </td><td valign="top" width="78">40% </td><td valign="top" width="67">30% </td><td valign="top" width="79">45m </td></tr></tbody></table>