Trigonal bi-pyramidal is the only electron domain geometry consistent with the shape shown.
Work Step by Step
The molecule in b has a T-shaped molecular geometry, which is suggested by the fact that there are three bonded atoms with bond angles of 90 degrees. Because the molecule is T-shaped, we can conclude that the molecule must have 2 lone pairs. There are 3 bonded atoms and 2 loan pairs, so there is a trigonal bi-pyramidal electron domain geometry.