Is D= A ∩ B ∩ C ?

Deepak sir of ECE (a viplavakari, I suppose. Well , I dont know him personally) writes in his blog...

"
Let A = {Things which can increase the happiness of the larger society}

Let B = {Things which I'm capable of doing well}
Let C = {Things that I will enjoy doing}
Let D = {Things I'm doing now}

ABC = A ∩ B ∩ C
(∩ denotes intersection)

Questions :

1. Is D = ABC?
2. Is D a subset of ABC
3. Is D ∩ ABC non-empty, atleast? "
   

Well I found these questions rather interesting..It is an abstraction to the line of thoughts which arise when one tries to define the meaning of life......

Signing Off
RK