Explanation:
Geometrical isomerism occurs in coordination compounds where there are two different ligands and they are arranged differently in space.

Optical isomerism occurs in coordination compounds where there is a chiral center, i.e. a carbon atom bonded to four different functional groups. In coordination compounds, a chiral center can be created by the presence of a bidentate ligand, which is capable of binding to a single metal ion at two different sites.

Now let's look at the given options:

a) [Pt(NH3)Cl]: This complex has a square planar geometry and there are no two different ligands present. Therefore, it cannot show geometrical isomerism.

b) [Pt(NH2CH2CH2NH2)Cl]: This complex also has a square planar geometry and there are no two different ligands present. Therefore, it cannot show geometrical isomerism.

c) [Pt(en)3]: This complex has an octahedral geometry and all the three ethylenediamine ligands are identical. Therefore, it cannot show geometrical isomerism. However, it can show optical isomerism because each nitrogen atom in the en ligand is a chiral center.

d) [Pt(en)Cl2]: This complex has an octahedral geometry and there are two different ligands present, i.e. en and Cl-. Therefore, it can show geometrical isomerism. Additionally, it can also show optical isomerism because each nitrogen atom in the en ligand is a chiral center.

Hence, the correct answer is option D.