Question

Fill in the blanks four:-Animals are great builders using simple
material — employing sound engineering principles. option a. but b. there of. c. yet. d. only.

Answer 1

I think it's but
I am not sure about the answer

Answer 2

$Animals \:are \:great\: builders \:using \\simple \:material\: \boxed{but} \:employing \\sound \:engineering\: principles.$