Hope this may help you..
answer: the correct answer is only the dominant trait is visible.
gregor mendel performed experiments with pea plants in order to study the inheritance patter of different traits of pea plant.
to identify the between two alleles i.e one is dominant ( is expressed always) and is recessive ( only expressed in absence of dominant allele), he performed monohybrid cross.
t is the allele for dominant trait ( tall) and t is the allele for recessive trait ( for dwarf).
he took two pure breeding strains of parental generation, one with tt (tall) and other with tt ( dwarf) and intercrossed them.
refer the attachment for the results.
all the plants were tall in the f1 generation. therefore, he concluded that dominant trait is visible in the f1 generation.