One word substitution: choose the best single word meaning Easily duped or fooled.

Introduction / Context:
One word substitution questions ask you to replace a descriptive phrase with a precise single word. The phrase here is Easily duped or fooled. This describes a person who believes things too quickly and is easily tricked by others. We must choose the noun or adjective that accurately captures this meaning.

Given Data / Assumptions:

The key idea is that the person can be easily deceived or cheated.
The phrase does not refer to stubbornness, respectability, or mockery, but specifically to susceptibility to being fooled.
The correct option should be a standard vocabulary item used in such contexts.

Concept / Approach:
The English word gullible means exactly what the phrase states: easily persuaded to believe something and therefore easily fooled or duped. It is widely used in exam level English and appears in many word lists. The other options denote entirely different traits, such as intolerance or deserving respect, and so they cannot serve as correct substitutions.

Step-by-Step Solution:
Step 1: Focus on the core meaning of the phrase easily duped or fooled. Step 2: Recall that gullible is the standard adjective describing someone who believes things too readily and is easy to trick. Step 3: Compare gullible with the remaining options and confirm that none of them refer to being easily fooled. Step 4: Confirm that gullible is used with people, for example gullible tourists or gullible children. Step 5: Select Gullible as the correct one word substitution.

Verification / Alternative check:
Dictionary definitions of gullible describe it as easily persuaded to believe something and therefore easily tricked. This matches the phrase easily duped or fooled word for word. Sample sentences such as He is so gullible that he believed every rumour he heard reinforce this equivalence. No other option aligns so closely with the idea of being vulnerable to deception.

Why Other Options Are Wrong:
Option A Bigot refers to a person who is intolerant of other people s opinions or beliefs, especially in matters of race, religion, or politics. This has nothing to do with being easily fooled.
Option C Ridicule is a noun meaning mockery or behaviour intended to make someone appear silly; it is an action, not a personality trait of being easily duped.
Option D Venerable means worthy of respect, especially due to age, wisdom, or character. A venerable person may or may not be easily fooled; the word simply does not contain that idea.
Option E Skeptical describes a person who doubts or questions things and is therefore the opposite of gullible. A skeptical person is hard to fool, not easy to trick.

Common Pitfalls:
Sometimes students confuse gullible with words like gentle or humble because all describe people in some way. However, for one word substitutions, it is vital to focus on the exact behaviour described: here, the specific behaviour is being easily deceived. Learning vocabulary in small thematic groups, such as words related to honesty, deception, or attitude, can help you keep similar looking but unrelated words clearly separated in your memory.

Final Answer:
The best single word that means Easily duped or fooled is Gullible.