In a case-control study of computer display exposure and glaucoma, cases and controls were also asked about television watching habits. Errors in recall of exposure to video screens occurred with equal frequency among cases and controls. Which of the following methods for adjusting for confounding by age is most likely to affect the generalizability of the study findings?

a. Randomization
b. Restriction of study subjects to those less than 50 years old
c. Stratification to several age groups
d. Matching by age plus or minus 5 years
e. Adjustment for age in a regression analysis

Correct option is B

Restriction of study subjects to those less than 50 years old.

Explanation:

Glaucoma is the disease which is tends to be a disease of older persons and the generalizability of the study may be decreased by this kind of restriction.  

the national environmental policy act (nepa) is a united states environmental law that promotes the enhancement of the environment and established the president's council on environmental quality (ceq). the law was enacted on january 1, 1970. to date, more than 100 nations around the world have enacted national environmental policies modeled after nepa.