Answer:

To fill in the blank in the given statement, we need to choose the appropriate modal verb that expresses certainty or confidence about the future.

Modal verbs:
Modal verbs are used to express various degrees of possibility, ability, permission, and obligation. They modify the main verb in a sentence and help to convey the attitude or mood of the speaker.

Options:
a) might
b) may
c) would
d) will

Explanation:
In this case, the most appropriate modal verb to express certainty or confidence is "will." This is because "will" is used to indicate something that is certain or likely to happen in the future. When we say "I am sure we will succeed," it means that we have a strong belief or confidence that success is guaranteed.

Let's analyze the other options to understand why they are not the correct choices:

a) might: "Might" is used to express less certainty or a lower probability compared to "will." If we use "might" in the given statement, it would indicate that there is a possibility of success, but it is not certain or guaranteed.

b) may: "May" is used to express permission or possibility, but it does not convey the same level of certainty as "will." If we use "may" in the given statement, it would imply that success is a possibility, but there is also a chance of failure.

c) would: "Would" is used to express a hypothetical situation or a polite request. It does not convey the same level of certainty as "will." If we use "would" in the given statement, it would imply that success is conditional or dependent on certain circumstances.

Therefore, the correct answer is option 'd) will' as it best conveys the certainty or confidence of success in the given statement.