The ties that bind a family together are so . . . . . . . that they can hardly withstand any strain.

The correct answer is A. tenacious.

Tenacious means holding firmly to something; persistent. In this context, it means that the ties that bind a family together are very strong and will not easily break.

The other options are incorrect because they do not convey the same meaning of strength and durability.

• Twisted means bent or turned out of shape. This does not accurately describe the ties that bind a family together, which are meant to be strong and supportive.
• Tenuous means not strong or firm. This also does not accurately describe the ties that bind a family together, which are meant to be strong and lasting.
• Tentative means not certain or decided. This does not accurately describe the ties that bind a family together, which are meant to be strong and secure.