B.
Homogeneous means one mixture, so like salt water. It looks like one mixture.
Heterogenous means different mixture. Comparable to a bag of Chex mix. So if the magnet can attract the pieces of Iron, it has to be a separable mixture. Compounds would require a chemical reaction to separate.
The answer is; C & E
Building a dam alters the water regime down the dam. The dam also affects fish migration along the river, alters the transportation of sediments by the river downstream, and changes temperatures within the local environment of the dam. These changes, however, the subtle effect the ecosystem around the dam and down the river. The potential energy of the water held by the dam is, however, high and used to produce more electricity.
