I'd say A.
The word "describing" or almost anything ending with "ing" signifies an action occuring now, or in the present. B, C, and D use "when describing" which leads to the assumption that these things listed are taken into account while the landscape is being described but answer choice A uses "when they describe" which is passive rather than active.
Testimonial - a written declaration certifying to a person's character, conduct, or qualifications, or to the value, excellence, etc., of a thing; a letter or written statement of recommendation.
The complete predicate in this sentence is A. mopped his brow, exhaled sharply, and picked up his phone.
B and C aren't correct, because they aren't complete predicates - something is missing.
D isn't correct, because <em>looking up from his computer monitor </em>is not a predicate, it is an adverb phrase.
Every 4th of July, almost all American cities sponsor a fete that includes a fireworks display to celebrate American independence.
A fete is a French word which basically means a celebration, party.