Answer:
B [tex]3x^4 + 7x^2 - 20[/tex]
Step-by-step explanation:
To find the total height, multiply the two expressions.
[tex](x^2 + 4)(3x^2 - 5)\\3x^4 + 12x^2 -5x^2 - 20\\3x^4 + 7x^2 - 20[/tex]
