which one is correct?

It is NOT necessary to balance the equations of organic reactions.  Therefore, you CANNOT predict the product of reaction based on math.

Here below shows the reaction between an amine and HNO₂ in cold acidic solution.

1° amine + HNO₂ → N₂ gas

2° amine + HNO₂ → an insoluble oil of N-Nitrosamine (RR'N-N=O)

3° amine + HNO₂ → ammonium salt

The given amine is a 2° amine as the N atom in the molecule is bonded to 2 alkyl groups.

So, an insoluble oil of N-Nitrosamine (RR'N-N=O) is formed as the product.

Hence, the answer:  the first one

The conversion is shown below:

"Chemical Aid" website shows a reaction:

5CH3CH2NH2 + 3HNO3 --> 4N2 + 4H2O + 5CH3CH2OH

1) is correct.  A secondary amine reacts with nitrous acid to form an N-nitroso amine.

I see that you were able to re-categorize your question. Well done. High school chemistry was a long time ago, but I'm going to say that the first one is correct, based on the math involved.