What is right ? Do you think the sun produce energy by fusion reactions only?

There may still be a tiny portion still produced by gravitational contraction and/or loss of gravitational potential as denser elements sink towards the core, but after 5 billion year and will all the convection going on, I would expect that this is an extremely small fraction that can be safely ignored in the type of calculations we do on Yahoo!Answers. Still, the value is not completely zero as there is still "stuff" falling onto the Sun (we can certainly see the occasional comet, and there must be the occasional asteroid).

There may also be an almost-as-tiny fraction being produced by tidal braking (mostly due to Jupiter and Saturn). Again, other than the mathematical curiosity, this can be ignored.