It is not impossible to reach an agreement if both sides ____ a positive and co-operative attitude.A will take up B take up C are to take up D will have taken up

It is not impossible to reach an agreement if both sides ____ a positive and co-operative attitude.
A will take up B take up C are to take up D will have taken up

楼主,这个题目的正确答案是B
当是It is +形容词 to do sth.if+条件状语从句的句式时,
条件状语从句应该使用一般现在时态
或者有另一个种情况：主句使用的是一般将来时
如：I will go to play football if the weather is fine.
从句同样使用一般现在时态