During sexual differentiation in males :

Primitive Gonads differentiate into testis due to the presence of SRY gene Gonads development : Initially Gonads are bipotential and do not acquire male or female morphological characteristics till the seventh week of development.deg SRY Gene located on the sho arm of Ychromosomedeg directly controls the differentiation of the Bipotential gonad to Testis (therefore option 'b. is correct). If SRY Gene is absent it leads to female sex differentiation i.e. ovary. So, development of ovary occurs 2 weeks later than testicular development.deg Duct's development : In males : The seoli cells secrete Anti mullerian hormone (mullerian inhibting substance) which cause regression of mullerian duct (option "a" incorrect) The Leydig cells secrete Testosterone which leads to development of Wolffian duct (option "d" incorrect)deg In females : Absence of Antimullerian hormone leads to development of Mullerian duct and Absence of Testosterone leads to regression of Wolffian duct.deg External Genitalia : In Males : Testosterone is conveed to Dihydrotestosterone by 5ot Reductase and Dihydrotestosterone which leads to development of External Genitalia.deg In Females : Presence of estrogens and absence of testosterone is responsible for development of External Genitalia. Note : Serum MIS levels remain elevated in boys during childhood and then decline at pubey to the low levels seen in adult men. In contrast girls have undetectable levels of MIS until the onset of pubey when serum MIS levels become measureable.