Directions: The sentence below has been divided into four parts. One of the parts may have an error of grammar or diction. Select the part having the error. If there is no error, choose option (e).

(a) They are building solid concrete walls in places where, (b) they think, perhaps once in a thousand years there will be a landslide and (c) needlessly dig up bamboo groves which will most assuredly (d) not be washed away, by stacking up concrete blocks (e) No error