which one of the following condition in humans is correctly matched with its chromosomal abnormality/linkage ? (1)erythroblastosis foetalis -X- linked (2) downs syndrome -autosoms+XO (3) klenifelter syndrome - 44autosomes +XXY (4) color blindness- Y linked

dear anjali 
its a simple ques , frst of all erythroblastosis foetails is a disease in which the mothers blood antigen will not recognise the baby as its own and starts killing it , so, its not any kind of chromosomal disorder . 
then down syndrome is trisomy of chromosome no 21 , and colour blindlness related to X chromosome . 
so, option no 3 turns out to be the correct answer 
regards 
all the best