Take context from the input text and decide on the accurate relationship between 'Spreadtrum' and 'Tsinghua Unigroup' from the options provided.
Options: operator, product/material produced, member of, parent organization

Intel Corp. bought a 20% stake in Tsinghua Unigroup last year for $1.5 billion.Tsinghua Unigroup, which was founded in 1988 by China’s elite Tsinghua University, became China’s largest chip design firm in 2013 after acquiring two of the country’s largest mobile-chip firms, Spreadtrum Communications and RDA Microelectronics.Micron, based in Boise, Idaho, is the last remaining U.S. maker of the widely used chips known as dynamic random access memory, or DRAMs.
parent organization