The correct option is C Trisomic and monosomic conditions respectively
Presence of one extra chromosome than the normal chromosome number in a diploid species is known as trisomy (2n+1). Monosomy is a aneuploid condition where one homologous chromosome is missing (2n-1). Nullisomy is a aneuploid condition where one pair of homologous chromosome is missing (2n-2). Presence of one chromosome in four copies is known as tetrasomy (2n+2). Presence of full or partial extra three copies of chromosome 21 causes Down's syndrome. Hence, it is trisomy 21 and is represented as 45 +XY or 45+XX. Absence of one X-chromosome causes Turner's Syndrome which is represented as 44 +XO and is a monosomic condition.