Which is the last law of Mendel?

If in a dihybrid cross, Mendel had used two such characters which were linked, he would have faced difficulty in explaining the results on the basis of his

The principle that alleles live together without showing any blending is known as . . . . . . .

Which one of the following can be explained on the basis of Mendel's Law of Dominance?
$A$. Out of one pair of factors one is dominant and the other is recessive.
$B$. Alleles do not show any expression and both the characters appear as such in $F_2$ generation.
$C$. Factors occur in pairs in normal diploid plants.
$D$. The discrete unit controlling a particular character is called factor.
$E$. The expression of only one of the parental characters is found in a monohybrid cross.
Choose the correct answer from the options given below:

What will be the percentage of $ab$ gametes produced by an $AaBb$ parent (in $\%$)?

$A$ plant is heterozygous and is represented as $Bb$. It produces two types of gametes,$B$ and $b$. What is the probability of the $b$ gamete?