Translation:She wants to measure her body in centimetres.
It is not wrong, but not a valid option in the DuoLingo dataset. We do not know if dia is a she or a he. And we do not know is she is measuring him or her or herself. Or he is measuring her or himself. So all are correct translations. Everything is about context in Indonesia. If she/he would measure her/his own body size; Dia mau mengukur badannya dalam sentimeter. , would be a good translation.