A test cross is carried out between the F1 generation hybrid and a double recessive parent. This cross helps determine the genotype of the F1 hybrid. If the hybrid is homozygous dominant then all the progeny will show the dominant phenotype and if the F1 hybrid is heterozygous dominant, then 50% of the progeny will show the dominant phenotype and 50% will show recessive phenotype. So, the correct option is 'F1 hybrid with double recessive'.