The configurations at the three chiral centres in the bicyclodecanol given below, are A. 1S, 2S, 6R B. 1S, 2S, 6S C. 1R, 2R, 6R D. 1R, 2S, 6R

The correct answer is A. 1S, 2S, 6R.

To assign the configuration at each chiral center, we need to determine which group is coming out of the page and which group is going into the page. We can do this by drawing a Fischer projection of the molecule.

In a Fischer projection, the horizontal bonds are coming out of the page and the vertical bonds are going into the page. The substituents are then placed on the appropriate bonds according to their priority. The priority of the substituents is determined by the following rules:

1. Atoms with higher atomic numbers have higher priority.
2. If two atoms have the same atomic number, the atom with the greater number of bonds to hydrogen has higher priority.
3. If two atoms have the same atomic number and the same number of bonds to hydrogen, the atom with the lower atomic number has higher priority.

Once the priority of the substituents has been determined, we can assign the configuration of the chiral center by following the Cahn-Ingold-Prelog (CIP) system. The CIP system assigns the configuration of a chiral center as R or S, depending on which group is coming out of the page (R) or going into the page (S).

In the case of bicyclodecanol, the configuration at the first chiral center is S. This is because the group with the highest priority (the hydroxyl group) is coming out of the page. The configuration at the second chiral center is also S. This is because the group with the highest priority (the methyl group) is coming out of the page. The configuration at the third chiral center is R. This is because the group with the highest priority (the hydroxyl group) is going into the page.

Therefore, the configurations at the three chiral centers in bicyclodecanol are 1S, 2S, 6R.