You infect E. coli cells with two strains of phage λ. One strain has a mutant host range, produces larger-than-normal plaques, and is temperature sensitive (genotype: h r t ). The other strain expresses the wild-type phenotype for these characters. Progeny phages from the lysed E. coli cells are collected and plated on a lawn of bacteria. You observe the following number of plaques for each progeny phage phenotype (which directly corresponds to its genotype):

Progeny phage genotype Number of plaques
h+ r+ t+

562
h r t 578
h+ r t 41
h r+ t+ 35
h+ r t+ 88
h r+ t 75
h+ r+ t 6
h r t+ 5
Which gene is located between the other two on the λ phage chromosome?

r
h
t