according to the pedigree chart, which statement must be true?

Explanation:

As per the pedigree chart, only the males are shown as affected by the disease. Thus, it must be a sex-chromosomal inheritance, expressed in the Y chromosome or the male chromosome.  

As the females in the family are unaffected, hence the mother in the original parental generation cannot be a carrier.

It is likely that the father from the original parental generation might be the carrier.

As there are affected individuals in both the generation after the original parental generation ( the last generation having two more affected males), the statement that the chances of inheriting the decease with each successive generation is not true.

he is very short, and he can only reach halfway up on the elevator buttons. but on a rainy day, he has his umbrella with him, and he uses it to poke the button at the top.