A psycholog st wantod to test whether the sound of a human heartbeat would help newborn babies grow. To investignte this theory a baby nurvery at a hongital was set up so that the sound of a human heartbeat could be heard throughout the nursery. The heartbeat scund was played in the nursery for a large batch of randomiy selected newbom babies, who were then weighed to determine their weight gain after four days in the nursery Later, a second batch of randomly selected babies occupied the nursery, but no heartbeat was played. These children were also weighed after four days in the nursery. What fype of variable is "baby weight after 4 days"? A. Discrete B. Nominn' C. Ordinal D. Continuous