这句话用which,能不能用that或用to?

题目

这句话用which,能不能用that或用to?
原句:looking for a sustainable way which i can keep on travelling .
如果我改的话:which 能改that吗?
或者用to:变成looking for a sustainable way to keep on travelling
哪句改的正确,

答案

that跟which都没问题,如果looking的主语是I,也就是说主句和从句主语相同,to也行