this is my doubt also...however I applied some logic n had option C as answer....it is only option which shows for IS curve (the first equation) negative relnshp between Y and r...and the second equation..that is LM relation which has positive relnshp between Y and r
look IS curve is download sloping and it shows negative relnshp between output and interest rate....and LM curve shows positive relnshp between output and interest rate...
have a glance at d options...in option C only we have the first equation (IS equation) showing negative relation between Y and r( notice the negative sign before r )...and the second equation (LM equation ) showing positive relationship between Y and r...(notice the positive sign before r)