The safest investment for a year from now I think is Bitcoin. Bitcoin will have its halving event around May 2020 and it's an enough sign to know that the price will be growing and might have its new all-time high. Other's coins might follow Bitcoin and you can have higher return but you need to pay more attention of what you are going to invest in.
Op will be train to the Army and he will not focus for sure because he is on the training, but choosing bitcoin now is more sfa ecompared to the other coins as the movement of the bitcoin we can see price increasing again and after 1 year or the year 2020 mayne the price become very high or more than $20,000 which what the highest value of the bitcoin hitted.