Limitations on Epidemiologic Studies Include the Following

Multiple Choice

Limitations on epidemiologic studies include the following:
1. failure to control experimental group for other known carcinogens
2. insufficient observation periods which permit full demonstration of cancers with long latent periods
3. using improper control groups
4. deficient or incorrect health records

A) 1 and 2 only
B) 2 and 3 only
C) 2 only
D) 1, 2, 3 and 4