Bond angles in a big molecule

1: 109 degree
2: 120 degree
3: 180 degree

I chose a. But the correct answer is c. How?!

Answer credited to @Asafmen

You’ve forgotten to take the lone pairs into account.

The structure of Bond 3 is not linear, it is a tetrahedron.

Oxygen has 2 lone pairs, so it has angles slightly smaller than the tetrahedron of 1 (as in less than 109.5).

Thus, the answer will be C.

Use this to review the VSEPR and Hybridization, for future reference.