Final answer:
Seismic deficiency in wood light frame multi-unit residences is caused by lack of structural integrity, inadequate lateral bracing, and insufficient foundation design.
Step-by-step explanation:
The seismic deficiency in wood light frame multi-unit residences can be attributed to a combination of factors, including lack of structural integrity, inadequate lateral bracing, and insufficient foundation design. These deficiencies can increase the vulnerability of the building to seismic forces during earthquakes.