For this question, choose the option opposite in meaning to the word or phrase in italics. The robbers gained…

Step 1: Analyze the question We need the word opposite in meaning to porous, as used in "porous security network."

Step 2: Explain the concept Porous literally means full of tiny holes that let liquids or air pass through. Figuratively, a "porous" security system is one with gaps or weaknesses that can easily be penetrated. So the opposite is something sealed, tight, or not allowing anything through.

Step 3: Check each option

• A. amorphous: means shapeless or without a clear form. It has nothing to do with holes or penetration, so it is not the opposite.
• B. impermeable: means not allowing fluids or anything else to pass through. This is the direct opposite of porous.
• C. gorgeous: means very beautiful. It is unrelated.
• D. pervious: means allowing something to pass through. This is a synonym of porous, not an opposite. It is the trap option.

Step 4: Answer The correct option is B. impermeable.

Step 5: Exam tip Watch the prefixes. Im- means "not," so impermeable = not permeable. Also, in "opposite meaning" questions, examiners often include a synonym (here, pervious) to catch students who rush. Always confirm whether the question asks for the same or the opposite meaning before choosing.