ANS:A - face centred

The closeness of packing is maximum in the case of a face-centred cubic (fcc) crystal lattice. In a face-centred cubic lattice, each lattice point is surrounded by 12 nearest neighbors, arranged at the corners of a cube, and additionally, there are 6 nearest neighbors located at the center of each face of the cube. This arrangement allows for the highest packing density among the three common types of crystal lattices. In contrast, a simple cubic lattice has lattice points only at the corners of the cube, resulting in relatively poor packing efficiency. A body-centred cubic lattice has one lattice point at the centre of the cube and eight at the corners, which is more efficient than a simple cubic lattice but still less efficient than an fcc lattice. Therefore, the maximum closeness of packing is achieved in a face-centred cubic (fcc) crystal lattice.