Assuming the underlined verb form is masquerading, the correct answer is B. gerund.
Although gerunds and participles look the same (both have the form verb + -ing), the difference is in their function - participles are used as either adjectives or adverbs, whereas gerunds are used as nouns within a sentence.
Use Concrete Examples The best place to start with your character description is with concrete examples. To say that a character has "brown hair" doesn't create nearly the image as saying that a character has long dreadlocks. Think about what kind of clothes the character wears, whether a character has freckles or moles, whether her teeth are straight or crooked or what kind of scars he has.
Make Examples Do More Avoid overloading your reader with a list of details about each character's appearance.
To create a vivid image of your character without spending a lot of time on minutia, choose details that have a ripple effect on the description.
Clandestine means you are doing something secret or it's a very quite subject matter so D.
