how do we determine if it is a one tail test or a two tail test in order to find the correct number on the t table.

For example

A similar study was conducted at the maternity ward in the Calgary Grace hospital. The null hypothesis was again that the true mean was 3.5 births per day, and the alternative was that the mean was greater than 3.5. A sample of size 18 was used, and the value of the test statistic was 2.898. What is the p-value of this test?

how would we know if this was a one tail or two tail test