Some humans are able to roll their tongue, while others are not. Two parents (both tongue-rollers) have four children, all of whom are not tongue-rollers. Which of the following statements hold true regarding this?
(i) The allele for tongue-rolling is dominant
(ii) The probability that their next child will be a tongue-roller is 0.5.
(iii) The probability that their next child will not be a tongue-roller is 0.75.
(iv) Both parents have one allele for tongue-rolling and one allele for non-tongue-rolling.

Some humans are able to roll their tongue, while others are not. Two parents (both tongue-rollers) have four children, Some of them are tongue rollers and some of them are not. Which of the following statements hold true regarding this?
(i) The allele for tongue-rolling is dominant
(ii) The probability that their next child will be a tongue-roller is 0.5.
(iii) The probability that their next child will not be a tongue-roller is 0.75.
(iv) Both parents have one allele for tongue-rolling and one allele for non-tongue-rolling.

In humans, the ability to roll the tongue is a dominant trait. The inability to roll the tongue is a recessive trait. If two individuals homozygous recessive for this trait have a child, what is the chance that the child will be able to roll his tongue?