Refer to the input text as context and select the correct relationship between 'Cigna' and 'health insurance' from the available options.
Options: platform, location of formation, product/material produced, subsidiary

Insurer Anthem sealed a $54.2 billion deal to buy rival Cigna (NYSE: CI - news ) , in a further consolidation of the US health insurance industry in the wake of the US Affordable Care Act.
product/material produced