This is a highly complex field dealing with biological systems; the effectiveness of actions is often dependent on a range of factors; and, in many instances, the science is emerging.
Mae sawl elfen i’r gofynion tryloywder o dan y gyfundrefn hon – mae’r rhain yn gymwys mewn ffyrdd gwahanol yn ôl pa broses gaffael sy’n cael ei chymhwyso.