Suitable Adverb Options:
a) never
b) usually
c) always
d) frequently

Explanation:
In this question, we are given a statement "I am a very punctual person" and we need to choose the most suitable adverb to complete the sentence "I am ______ late."

To determine the correct adverb, we need to consider the meaning of each option and choose the one that best fits the given statement.

Option A: never
The adverb "never" means not at any time or not on any occasion. If someone is "never late," it implies that they are always on time and never arrive late to their commitments. This adverb is the most suitable choice in this context as it emphasizes the speaker's punctuality.

Option B: usually
The adverb "usually" means most of the time or generally. If someone is "usually late," it implies that they are often late but not always. However, the given statement states that the speaker is a very punctual person, which contradicts the idea of being "usually late."

Option C: always
The adverb "always" means at all times or on every occasion. If someone is "always late," it implies that they are consistently late and never arrive on time. This option contradicts the given statement, which states that the speaker is a very punctual person.

Option D: frequently
The adverb "frequently" means often or repeatedly. If someone is "frequently late," it implies that they are often late but not necessarily always. However, the given statement states that the speaker is a very punctual person, so being "frequently late" is not consistent with their punctuality.

Conclusion:
After analyzing the options, we can conclude that the most suitable adverb to complete the sentence "I am ______ late" is option A, "never." This choice aligns with the statement that the speaker is a very punctual person, indicating they are always on time and never late.