Homozygous.
You can tell in future that if both letters are either lowercase or upper case (e.g. TT or tt) the answer is always HOMOzygous. If the letters are different cases (e.g. Tt or tT) the answer is always HETROzygous. This is because 'homo' means 'same' and 'hetero' means 'different'.
C. this individual is a male since he has X and Y chromosomes
All living things have DNA within their cells. In fact, nearly every cell in a multicellular organism possesses the full set of DNA required for that organism.
In a scientific study, a conclusion can state a theory
I am sorry but you did not include an attachment of the markings