Jesus' teaching on swearing is that Christians should

The question is asking about Jesus' teaching on swearing. Swearing here means making a promise or taking an oath. The question wants to know what Jesus' teaching is on this topic.

According to the options provided, Option A says that Christians should not swear falsely. This means that Christians should not make a promise or oath that they know they cannot keep.

Option B says that Christians should swear when necessary. This option is incorrect because Jesus teaches that Christians should not make oaths at all.

Option C, which is the correct answer, says that Christians should not swear at all. This means that Christians should not make any promises or take any oaths. Instead, they should let their yes be yes and their no be no. This means that they should always tell the truth and keep their word without needing to add an oath or promise to it.

Option D says that Christians should swear by the head. This option is incorrect because Jesus teaches that Christians should not make any oaths or promises at all.

In summary, Jesus' teaching on swearing is that Christians should not swear at all. Christians should always tell the truth and keep their word without needing to make any oaths or promises.