A)strictly nocturnal
B)strictly diurnal
C)crepuscular
D)trainable to alternate sleep patterns

A)the more hamsters, the larger the habitat
B)levels in the habitat need equal the number of hamsters
C)never put more than two hamsters together
D)one hamster, one habitat

A)during the mid-1950s
B)at the turn of the twentieth century
C)during the 1980s
D)prior to World War II