After carefully studying how three single parents dealt with the loss of their jobs, Dr. Phong began to overestimate the national rate of unemployment. In this instance, Dr. Phong should be warned that may be misleading.

The case studies

Explanation:

Case studies are a subset of a population that is sample in a research process.

The tendency of case studies being entirely true is dependent on certain factors in which on of them is using the right and dependable subset from a given population.

The overestimate on unemployment rate by Dr. Phong just by a careful research of only 3 cases will likely produce a wrong outcome.

the answer might be either a or c. can't be too sure , because i searched the web, but no valid answers came through.

im sorry i wish i can but try google