The correct pair of elements that are liquid at room temperature and standard pressure is option 4, which consists of bromine and mercury.

Option 1 states that bromine and fluorine are liquid at room temperature and standard pressure. However, this is incorrect as fluorine is a gas at room temperature and standard pressure.

Option 2 states that mercury and rubidium are liquid at room temperature and standard pressure. Although mercury is indeed liquid at room temperature and standard pressure, rubidium is a solid at room temperature and standard pressure.

Option 3 states that bromine and thallium are liquid at room temperature and standard pressure. However, this is incorrect as thallium is a solid at room temperature and standard pressure.

Therefore, the correct answer is option 4, which states that bromine and mercury are the correct pair of elements that are liquid at room temperature and standard pressure.