The main difference between dominant and recessive genes is that dominant genes get phenotypically exerted faster compared to genes that are being recessively transfered. These genes must have to be presented 2x more often (both alleles have to be recessive) for them to be exerted phenotypically.
The answer is A. Good luck!
Assuming type a would be an AA allele and type b is a BB allele, No because an AA mother with an AB father wont make a BB child.
this is called acquired immunity