Step 1: Think about mind versus body:
Bhavas in Indian dance theory are of three kinds: sthayi bhava (lasting feelings), vyabhichari bhava (passing feelings) and satvika bhava (body signs of feelings). A satvika bhava must be something the body shows by itself.
Step 2: Test each option for a body sign:
Romancha is goose bumps, which the body shows. Vaivarnya is the face losing colour, which the body shows. Stambha is stiffness of the limbs, which the body shows.
Step 3: Test Harsha:
Harsha is joy. Joy is a feeling in the mind that comes and goes, so it is a passing feeling (vyabhichari bhava). It is not one of the eight body signs.
Step 4: Conclude:
Only Harsha fails the test, so it is the one that is not a satvika bhava. The other three are all part of the list of eight.
Step 5: Recheck every option once more:
Option 1: Harsha. This is the correct choice.
Option 2: Romancha. This is not the answer.
Option 3: vaivarnya. This is not the answer.
Option 4: Sthamba. This is not the answer.
Final Answer:
Harsha is not a satvika bhava, option 1. \[\boxed{1}\]