My favourite fruit is apples.

[Winwin2011]

Are the following questions correct?

1.My favourite fruit is the apple.
2.My favourite fruit is an apple.

Is the following question wrong?

3. My favourite fruit is apples.

Thanks.

 

[probus]

It's a very reasonable supposition that option 3 is less grammatically correct than the first two, but in fact 3 is what one usually hears in AmE. I would say that 1 is rarely heard, and that 3 outnumbers 2 by at least 20 to one.

 

[Raymott]

I'd say 3 too. Note that your examples are not 'questions'.
Also, if inverted, you'd say, "Apples are my favourite fruit".