Please help! I am so confused. Please show work. Thank you!!

( ⁿ√a) ^m   can be written as    a^m/n  .....so.....

⁵(√a⁵ )  =    a^5/5  =  (a^1/5)⁵  = a  ⇒   Answer  C

Second one

³√ [216a³b9 ]  =  ³√216  * ³√a³  *  ³√b⁹    =  (6³)^1/3 * (a³)^1/3 * (b⁹)^1/3  = 

6ab³ ⇒ Answer C

Last one....look at answer B

√[98 j⁹c⁸]  = √{49*2]  * √ [j⁹ ] * √[c⁸ ]   =

√49  * √2  * √ [j⁸]  * √j  * √[c⁸ ]   =

7  * √2  *  (j⁸)^1/2  * √j  *  (c⁸)^1/2    =

7j⁴c⁴√[ 2j ]   

$7j^4c^4\sqrt{2j}$

Square and square root the expression.

$=\,\sqrt{\bigg(7j^4c^4\sqrt{2j}\bigg)^2}\\~\\ =\,\sqrt{7^2(j^4)^2(c^4)^2(\sqrt{2j})^2\vphantom{\bigg)}}\\~\\ =\,\sqrt{49j^8c^8(2j)\vphantom{\bigg)} }\\~\\ =\,\sqrt{49\cdot2\cdot j^8\cdot j\cdot c^8\vphantom{\bigg)} }\\~\\ =\,\sqrt{98j^9c^8 \vphantom{\big)}}$