Explanation: The definition of mutualism states " interaction between two or more species where each species has a benefit". The bird is getting food from the insects and the horse is getting the insects removed. Both are benefited.
The parent's genotypes are and respectively. When crossed together, all possible genotypes can be expressed. 1/4 AB blood, 1/4 A blood (heterozygous), 1/4 B blood (heterozygous) and 1/4 O blood. A Punnett square has been uploaded to support this.