An experiment consists of eight steps - H, J, K, L, M, O, P, and S - that all must be performed. Three days are allotted for the experiment. Each step requires exactly one morning or else one afternoon to be performed, and at most two steps can be performed during any given morning or afternoon. The following restrictions must be observed: J must be performed on the second day. P must be performed in the morning. K and M must be performed at the same time. J must be performed at some time after M has been completed and at some time after O has been completed. O must be completed at some time before P and at some time before S. At the earliest, P can be performed during which, of the following time periods?
A. The morning of the first day
B. The afternoon of the first day
C. The morning of the second day
D. The afternoon of the second day
E. The morning of the third day
Explanation: Constraints: P must be in the Morning. O must be completed before P. Since O is a step, it requires at least one morning or afternoon slot. The earliest O can be completed is the morning of Day 1. If O is completed Day 1 Morning, then P can be done Day 1 Afternoon (no, P must be Morning). So the earliest P can be done is on the day immediately after O is completed. If O is done Day 1 Morning, P can be done Day 2 Morning. If O is done Day 1 Afternoon, P can be done Day 2 Morning. The absolute earliest time P can be performed is the **Morning of the second day**.
