Air masses are nothing but air bodies of large size that have uniform characteristics all over its body. For instance they have uniform temperature and humidity .
2. Option D is correct
Source regions defines the characteristics of an air mass depending on the geographical features of the region from which air mass arises. An air mass acquires the properties of the geographical region from which it arises
3. Option D is correct
mT stands for maritime tropical which is defines an unstable air mass that is warm and moist as it travel s a long long distance over oceans.
If you make a punnet square out of this, there is no possibility to have a recessive trait because neither parents have it plus dominant is always going to overrule recessive traits.