A colour blind girl is rare because she will be born
only when
(a) her mother and maternal grand father were
colour blind
(b) her father and maternal grand father were
colour blind
(c) her mother is colour blind and father has
normal vision
(d) parents have normal vision but grand parents
were colour blind
only when
(a) her mother and maternal grand father were
colour blind
(b) her father and maternal grand father were
colour blind
(c) her mother is colour blind and father has
normal vision
(d) parents have normal vision but grand parents
were colour blind