thought of 多表示考虑, 想起,关心.英文解释最能说明为什么选B 而不是A了,to have formed a possible but not firmly settled plan for
例子:I'd thought of blue for this room. (blue 是"蓝图")
came up with ,想出,提出,英文解释是to think of (a plan,reply etc.),produce
thought up 想出,设计出.英文解释是to invent--力图想出
整句的关键是有个finally,所以要选择的词组就不仅要和idea 搭配,还要和整句的意思一致.