ISI 2017 (SAMPLE) Question 14 PEA

Posted by MomoChan on May 01, 2018; 11:27am
URL: http://discussion-forum.276.s1.nabble.com/ISI-2017-SAMPLE-Question-14-PEA-tp7609105.html

Will the answer be  (B) ?
I'm getting the upper level set to be convex i.e function quasi concave .
If not , then why ?