Will each of the following increase, decrease, or have no effect on the value of the test

Question:

Will each of the following increase, decrease, or have no effect on the value of the test statistic in a one-sample t test?
(a) The sample size is increased.
(b) The level of significance is reduced from .05 to .01.
(c) The sample variance is doubled.
(d) The difference between the sample and population mean is increased.