The correct passive form of the given sentence is That lady was loved by the president.

The active voice of the sentence is The president loved that lady. This sentence is in the simple past tense, which is used to describe an action that happened in the past. The passive voice of the sentence is formed by putting the subject of the active sentence after the verb "to be" and the past participle of the main verb. In this case, the subject of the active sentence is "that lady" and the main verb is "love." The past participle of "love" is "loved." So, the passive form of the sentence is That lady was loved by the president.

The other options are incorrect because:

• That lady is loved by the president. is in the present tense, but the action of the president loving the lady happened in the past.
• That lady is love by the president. is grammatically incorrect. The verb "to love" needs to be in the past participle form, which is "loved."
• That lady was being loved by the president. is in the past progressive tense, which is used to describe an action that was happening in the past but was not finished. The sentence is describing an action that happened in the past, so the past progressive tense is not appropriate.