In this scenario, the trait for having horns (h) is described as recessive, and the trait for not having horns (H) is presumably dominant. When cattle with horns (hh) are crossed with cattle that do not have horns (HH), the number of offspring having horns was equal to those not having horns.
This outcome suggests that both parents are heterozygous (Hh) for the trait.
So, the MOST LIKELY statement is:
(c) Both parents are heterozygous.