Answer is option (D). But I am not able to understand why. All of them have lone pairs. I can notice only two differences. Functional group in Option (d) has the largest size and lowest electronegativity.
I think that may be because of a large difference in size of Selenium and Carbon, pie bond formation in between them will be a bit difficult, but that bond is not playing any role here except stabilizing the compound.
Low electronegativity seems like a good thing to me as it does not deactivates the compound.
So what am I missing here?