**Explanation:**

In the given sentence, "My patience _______ (come) to an end," the correct answer is "has come."

**Present Perfect Tense:**
The present perfect tense is used to describe an action that started in the past and has a connection to the present. It is formed by using the auxiliary verb "have" or "has" followed by the past participle of the main verb.

**Subject-Verb Agreement:**
In the given sentence, the subject is "My patience," which is a singular noun. According to subject-verb agreement, a singular subject must be followed by a singular verb. Therefore, we use the singular form of the auxiliary verb "has" instead of "have."

**Use of "Has Come":**
The verb "come" is the past participle form of the verb "come." When we use "has come," it indicates that the action of the patience coming to an end started in the past and has a connection to the present. It implies that the speaker's patience has recently reached its limit or has been exhausted.

**Significance of "To an End":**
The phrase "to an end" is an idiomatic expression that means something is finished, completed, or terminated. In this context, it implies that the speaker's patience has reached its limit and has ended or run out.

**Overall Meaning:**
By using the phrase "has come to an end" in the present perfect tense, the sentence conveys the idea that the speaker's patience, which had been ongoing, has now finished or reached its limit.

Therefore, the correct answer is "My patience has come to an end."