Take context from the input text and decide on the accurate relationship between 'Equinix' and 'data center' from the options provided.
Options: subsidiary, position held, product/material produced, currency

-- U.S. data center operator Equinix (NasdaqGS: EQIX - news ) to acquire British peer Telecity Group (LSE: TCY.L - news ) (notified Sept. 24/deadline Oct (HKSE: 3366-OL.HK - news ) .
product/material produced