I’ll lend you money ------- you promise to return it by the

为你解答.
I’ll lend you money （B.as long as,只要） you promise to return it by the end of the this month.
只要你答应本月底以前还钱,我就借给你.
解释：其它三项的分析如下==
A.even if：即使,意思不对.
C.as far as：就……来说,意思不合适.
D.unless：除非,相当于if not,意思说反了.