Which of the following rules was given by Bergaman?

(a) Birds and mammals of colder areas are larger in size as compared to their equivalents in warmer areas. (b) Some insects, birds and mammals in warm humid climates bear darker pigment than the races of same species present in cool and dry climates. (c) Animals of colder areas have shorter extremities (i.e. ears, feet, tail etc.) as compared to animals of warmer areas. (d) Fish size as well as number of vertebrae increase in colder areas as compared to warmer areas. (e) Birds of colder areas have narrow and acuminate wings while those of warmer areas have broader wings.