How Are Temperature Sensitive Mutants Used to Determine When Genes

Multiple Choice

How are temperature sensitive mutants used to determine when genes act during development?

A) Embryos can be shifted to the restrictive temperature to inactivate the mutant gene and the effect of inactivation on subsequent stages can be observed.
B) Embryos can be shifted to the permissive temperature to inactivate the mutant gene and the effect of inactivation on subsequent stages observed.
C) Embryos can be incubated at the restrictive temperature for several hours.If the embryo develops normally, then the gene product is required during that period of development.
D) Embryos can be raised at the permissive temperature and if the embryo does not die, then the gene product is not required for development.