Explanation:

Diatomic molecules are molecules composed of two atoms of the same or different chemical elements. Each diatomic molecule has a characteristic bond type, which determines its chemical properties. There are three types of bonds that diatomic molecules can have: σ-type, π-type, and δ-type.

- σ-type bond: A covalent bond formed by the overlap of two atomic orbitals along the internuclear axis.
- π-type bond: A covalent bond formed by the sideways overlap of two atomic orbitals perpendicular to the internuclear axis.
- δ-type bond: A covalent bond formed by the overlap of two atomic orbitals along the internuclear axis, but with the electron density concentrated above and below the plane of the internuclear axis.

Based on the given options, we need to identify the diatomic molecule(s) that have two π-type bonds.

B2:

- Boron is an element that can form covalent bonds with itself to form a diatomic molecule (B2).
- The electronic configuration of boron is 1s2 2s2 2p1, which means that it has three valence electrons.
- In B2, each boron atom contributes one electron to form two π-type bonds between them.
- Therefore, B2 has two π-type bonds.

C2:

- Carbon is another element that can form covalent bonds with itself to form a diatomic molecule (C2).
- The electronic configuration of carbon is 1s2 2s2 2p2, which means that it has four valence electrons.
- In C2, each carbon atom contributes two electrons to form two π-type bonds between them.
- Therefore, C2 has two π-type bonds.

N2 and O2:

- Nitrogen and oxygen are also elements that can form covalent bonds with themselves to form diatomic molecules (N2 and O2, respectively).
- The electronic configurations of nitrogen and oxygen are 1s2 2s2 2p3 and 1s2 2s2 2p4, respectively. This means that they have five and six valence electrons, respectively.
- In N2 and O2, each atom contributes three and two electrons, respectively, to form one π-type bond between them.
- Therefore, N2 and O2 have only one π-type bond each.

Conclusion:

Based on the above analysis, we can conclude that the diatomic molecules that have two π-type bonds are B2 and C2.