A class of students consists of John, Sarah, Mike, and Lisa. The following conditions are given: 1) John cannot be in the same group as Sarah. 2) Mike must be in the same group as Lisa. Which of the following groups is valid?
A, B, C, D, and E are five different colored balls. The following conditions apply: A is not red, B is blue, C is green, D is not blue or green, and E is red. Which ball is yellow?