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