Answer:
The Correct answer is 50%
Step-by-step explanation:
The gametes produces are T, T by 1st parent and T, S by 2nd parent
 
 T T
T TT (tall) TT (tall)
S ST (medium) ST (medium)
So, the fraction of giraffes that are tall = 
 = 0.5×100% = 50%
 = 0.5×100% = 50%
So, The Correct answer is 50%