Huntington's disease is an autosomal dominant disorder that affects the nervous system. if a man is heterozygous for the alleles that cause the condition and has children with a women who lacks that defective allele, which of these statements is true?

Huntington's disease is a disease that inherited autosomal dominant. That means you just need one allele to made it expressed. Let say that H is Huntington's allele and N is normal allele. In this case, the heterozygous father has (H x N) gene and the normal mother has (N x N) gene.

That mean
1. The father will have 50% chance to give normal allele and 50% chance to give H allele
2. The mother will have 100% chance to give N allele

Since you just need 1 H allele to got Huntington's disease, 50% the children will have Huntington's while 50% of them is normal

The person who utilize the progression principle will keep adding the difficulty of the exercise that he's doing, while the person who does not, will only stay stagnant.  the person that utilize progression principle, will get a stronger endurance because now his body is conditioned to do harsher routines.{the answer was already on verified)