Find the Standardized Test Statistic to Test the Claim That $\mu _ { 1 } < \mu _ { 2 }$

Find the standardized test statistic to test the claim that $\mu _ { 1 } < \mu _ { 2 }$ Assume the two samples are random and independent.
Population statistics: $\sigma _ { 1 } = 2.9 \text { and } \sigma _ { 2 } = 2.8$ Sample statisticsstatistics: $\overline { \mathrm { x } } 1 = 20.16 , \mathrm { n } _ { 1 } = 35 \text { and } \overline { \mathrm { x } } 2 = 22.71 , \mathrm { n } _ { 2 } = 42$

A) -3.90
B) -3.16
C) -2.63
D) -1.66