Read the following text. Choose the best word(s) for each numbered blank and mark A, B, C or D on the ANSWER SHEET. (10points)

  The idea that plants have some degree of consciousness first took root in the early 2000s; the term “plant neurobiology” was _1_ around the notion that some aspects of plant behavior could be _2_ to intelligence in animals. _3_ plants lack brains, the firing of electrical signals in their stems and leaves nonetheless triggered responses that _4_ consciousness, researchers previously reported.

But such an idea is untrue, according to a new opinion article. Plant biology is complex and fascinating, but it _5_ so greatly from that of animals that so-called _6_ of plants’ intelligence is inconclusive, the authors wrote.

Beginning in 2006, some scientists have _7_ that plants possess neuron-like cells that interact with hormones and neurotransmitters, _8_ “a plant nervous system, _9_ to that in animals,” said lead study author Lincoln Taiz, “They _10_ claimed that plants have ‘brain-like command centers’ at their root tips.”

This _11_ makes sense if you simplify the workings of a complex brain, _12_ it to an array of electrical pulses; cells in plants also communicate through electrical signals. _13_ , the signaling in a plant is only _14_ similar to the firing in a complex animal brain, which is more than “a mass of cells that communicate by electricity,” Taiz said.

“For consciousness to evolve, a brain with a threshold _15_ of complexity and capacity is required,” he _16_ . “Since plants don’t have nervous systems, the _17_ that they have consciousness are effectively zero.”

And what’s so great about consciousness, anyway? Plants can’t run away from _18_ , so investing energy in a body system which _19_ a threat and can feel pain would be a very _20_ evolutionary strategy, according to the article.