State whether each of the following describes a study measuring a qualitative or quantitative variable.
(a) A researcher distributes open-ended questions to participants asking how they feel when they are in love.
(b) A researcher records the blood pressure of participants during a task meant to induce stress.
(c) A psychologist interested in drug addiction injects rats with an attention inducing drug and then measures the rate of lever pressing.
(d) A witness to a crime gives a description of the suspect to the police.