Read the following email message. Complete the email by filling in the blanks. Select the best choice for each blank.

Hi Carlos, I'm excited about our upcoming desert hiking trip next month! I've been reviewing the Desert Exploration Safety Guide and wanted to share some important information with you. First, we need to make sure we have enough water. The guide recommends 1 .... per person each day. I've also ordered some electrolyte packets to mix with our water since we'll be sweating a lot. For navigation, I already have a GPS, but I think we should also bring 2 .... as a non-electronic backup in case our batteries die. The guide also mentions that we should have a signal mirror and whistle - apparently 3 .... if we get into trouble. I'm particularly concerned about the temperature changes. Did you know that 4 ....? We'll need to pack both cooling items for the day and warm clothes for the night. I also think we should consider taking one of the training courses before we go. The 5 .... course is only one day and costs $95. It might be worth it since neither of us has much desert experience. If we can find two more people to join us, we could get a 15% discount. Let me know what you think! Best, Maria

Choose the best option.

Maria and Carlos are planning 1 ..... Maria suggests they should 2 .... before their trip. According to the safety guide, if someone gets lost in the desert, they should 3 .....