What’s the answers for this question please help me thank you

[tex]\text{Hey there!}[/tex][tex]\text{a will automatically equal one because it is unknown}[/tex][tex]\text{First you have to distribute your negative sign}\downarrow[/tex][tex]\text{Like: 2a - 5+ (-1)(3a+1)}[/tex][tex]\text{We get: 2a+(-5)+(-1)(3a)+(-1)(1)}[/tex][tex]\text{-1(3a)= -3a}[/tex][tex]\text{-1(1)= -1}[/tex][tex]\text{Our new equation becomes: 2a + (-5) + (-3a) + -1}[/tex][tex]\text{After solving that COMBINE YOUR LIKE TERMS}[/tex][tex]\text{\underline{2a}+ -5 + \underline{-3a} + -1 }[/tex][tex]\text{(2a + -3a)+ (-5 + -1)}[/tex][tex]\text{2a + -3a = -1a}[/tex][tex]\text{-5 + -1 = -6}[/tex][tex]\text{Now we can replace -1 with the value of -a}[/tex][tex]\boxed{\boxed{\text{Thus, your answer is: D. -a - 6}}}}\checkmark[/tex][tex]\text{Good luck on your assignment and enjoy your day!}[/tex]~[tex]\frak{LoveYourselfFirst:)}[/tex]