The right answer is option D in my opinion.
Although they are not considered the
most highest evolved of the cephalopods, cuttlefish are extremely intelligent.
A. the
most highest evolved ..... incorrect. The use of two superlatives
most and highest is inappropriate. We can say most evolved or highest evolved or change highest into an adverb highly so that
most highly modifying the verb-ed modifier (adjective)
evolved.
B. the
more higher evolved.....incorrect. More higher is also inappropriate for the same reasons stated in option A.
C. the
most highly evolving .....incorrect. This option changes the meaning of the sentence. In addition, the contrast between
most highly evolving, which signifies an ongoing process, and
extremely intelligent is not sound compared with the contrast in option C.
D.
the most highly evolved ... correct. The contrast between
most highly evolved and
extremely intelligent is more logical compared with the contrast in option C. The original meaning is also maintained.
E. the
most evolutionarily high .... incorrect. most evolutionarily high what? The meaning is unclear.