Answer:
C:Ff and FF
Step-by-step explanation:
This because if the floppy ears are dominant that means you can't use the first one.If you use the next one you will have probability 2/4 chance to have a bunny with straight ears.And 2/4 chance of having floppy ear bunny that just increases the chance for the straight ears.But, if you use the third one will give you a highest chance as you have multiple chance of dominant F(floppy ears) in which dominant always over power recessive.
Hope this helps :) Have a great day/night