Corn seeds with identical genetic information
were planted on two adjacent farms. The corn
plants on one farm were well fertilized and grew
large, while the plants on the other farm were
not given fertilizer and did not grow as large.
The best explanation for these observations is
that
(1) crops grow differently in different climates
(2) the corn plants all contained mutated genes
that made them grow
(3) environmental conditions affect gene
expression
(4) the plants on one farm had different genes
from the plants on the other farm