单选题 Research shows heavy coffee drinking is ______ a small increase in blood pressure, but not enough to increase the risk for high blood pressure.

【正确答案】 A

【答案解析】解析：本题考查句意和词组。be associated with“与……有关系”；be compared with“和……相比较”；be attributed to“归因于”；refer to“无被动语态”。