What is the answer?

290 ...  
 since it is aked to find the average fixed cost .. assuming that 580 is the average fixed cost ...for 2 units .. then for 1 unit the amount afc+avc =580+110=690 .. variable cost has to be excluded

please correct me .. if i am wrong

AFC is 580 which is not included in your options

for your kind information Fixed Cost is Not variable and then it cannot be said that it is 290 for One unit as per your option C

even i thought afc to be 580...

but the book says ans is 290...

290 s the right ans...