In a cyclotrimetaphosphoric acid molecule, how many single and double bonds are present?

Cyclotrimetaphosphoric acid contains 3 double bonds, and 12 single bonds as described in the figure. a,b,c represents double bond between o and P while numbering from 1 to 12 represents single bonds.

Hence the correct option is (iii).

NOTE: single bond consist of only sigma bond and double bond consist of one sigma and one pie bond.