Erm, here you have copper (II) carbonate CuCO3.

It is the H+ ions from nitric acid displacing the Cu²+ ions from CuCO3, not the Cu²+ ions displacing the H+ ions from the acid.

Besides, this is not exactly a displacement reaction but rather an acid-carbonate reaction.

We should not be talking about the reactivity series here as that would be the reaction of pure copper metal with the acid, but here you have CuCO3 instead.

ohh does that mean for Cu and Ag metal itself, it will not be able to react with acids as it is unable to displace H+ from the acid
but when it comes to Cu and Ag compounds, there will be reaction with the acids as H+ ions can displace Cu2+ and Ag2+ instead?

By the way, it's Ag+, not Ag²+

In a sense, you are right.

Notice that dilute nitric acid also reacts with sodium carbonate. Sodium is higher up in the reactivity series than hydrogen.

Here you can think of it as the sodium ions displacing the hydrogen ions from the acid though (strictly speaking, it is the hydrogen ions that attack the carbonate)

When we use the reactivity series here, we are concerned with a pure metal or hydrogen displacing another metal/hydrogen in a compound.

https://www.compoundchem.com/2015/03/10/reactivity-series/

Recommend you read this.

Answer is D
Statement 1 is incorrect. The more reactive the metal, the more stable the carbonate, hence the more reactive metal carbonate decomposed when heated.
Statement 2 is correct. Hydrogen ions react with carbonate ions to produce CO2 and H2O
Statement 3 is correct. Transition elements typically form coloured compounds. Group I, II and III compounds are white solids.