Mann-Whitney decision from tail bounds

Let $\{1,6,5,3\}$ and $\{11,7,15,4\}$ be realizations of two independent random samples of size 4 from two separate populations having cumulative distribution functions $F(\cdot)$ and $G(\cdot)$, respectively, and probability density functions $f(\cdot)$ and $g(\cdot)$, respectively. To test $H_0: F(t) = G(t)$ for all $t$, against $H_1: F(t) \ge G(t)$ with strict inequality for some $t$, let $U_{MW}$ denote the Mann-Whitney U-test statistic. Let, under $H_0$, $P(U_{MW} > 12) \le 0.10$, $P(U_{MW} > 14) \le 0.05$, $P(U_{MW} > 15) \le 0.025$ and $P(U_{MW} > 16) \le 0.01$. Then, based on the given data, which of the following statements is/are true?