In cattle, consider that the lack of horns is dominant to the presence of horns. a bull without horns is crossed with a horned cow. of four offspring, one is horned and the other three lack horns. the bull is

Heterozygous

Explanation:

A dominant trait is the one that expresses itself over the recessive trait, therefore for a recessive trait to express itself, an organism must have both the alleles as recessive for a given genotype.In the question, it is given that the lack of horns is dominant over presence hf horns.If we symbolize lack of horns as H and presence of horns as h,then :the genotype of the bull without horns needs to be determined the horned cow must be hh as this is a recessive traitit is given that out of four offspring one is horned, this means that this horned offspring must be hh and since the offspring inherits one allele each from the parents, one h must be coming from the cow and the other h from the bull and hence, we can conclude that the bull must be Hh i.e heterozygous .