A. they have a higher proportion of adenine–thymine than guanine–cytosine base pairs.
The option A represents the complete opposite of "high-gc gram-positive bacteria". High GC content means that this bacteria have more guanine ans more cytosine than the other base pairs- adenine–thymine. This means all the other options are correct.
A punnet square determines all of the ways in which alleles can combine. It may be used to predict ratios of offspring genotypes and phenotypes. However, Punnet squares cannot determine actual outcomes. They can only predict the possibility for things to happen. The exception to this takes place when the cross occurs with two homozygous dominant or recessive genes and the resulting offspring is either be 100% homozygous dominant or recessive.
