A Zookeeper Is Responsible for a Wallaby Enclosure in a Zoo

Multiple Choice

A zookeeper is responsible for a wallaby enclosure in a zoo. A new, young female has recently joined the enclosure and is soon mated with a virile male. Soon after, blood tests show that the female is pregnant but after a month the female still fails to show any signs of pregnancy. Why could this be so?

A) The female still has a very young offspring in her pouch which is halting the development of the new foetus.
B) Like all marsupials, wallabies have a long gestation period. There will be no indications of pregnancy for several more months.
C) The blood test is faulty.
D) The foetus has a developmental retardation mutation.
E) Young females can exhibit 'phantom' pregnancies that mimic real pregnancy at the biochemical level as a means of placating aggressive males on heat.