The major product formed in the following reaction is

Concept: The Diels–Alder reaction is the reaction between a conjugated diene and an alkene (dienophile) to form unsaturated six-membered rings. Since the reaction involves the formation of a cyclic product via a cyclic transition state, it is also referred to as a "cycloaddition".

Explanation: In Diels alder reaction the diene component must be able to assume an s-cis conformation. 

This is a 1,4 addition.

ODC rule 

O means: opposite           D means: Disrotatory               C means : Cis

S means :same                C means : conrotatory              T means : trans

The given compound is 4 system, in the presence of heat, will give con rotation. both the methyl groups are in opposite directions.

According to OCT rule. The product will show trans configuration.

Cis dienophiles give us cis products, and trans dienophiles give us trans products.

1. Electron withdrawing groups on the dienophile facilitate reaction.

2. Electron donating groups on the diene facilitate reaction.

Conclusion:-

So the correct answer is option 4